Essex Eagles
T20 best: SF 2006, 2008, 2010, 2013
2017: 8th, South Group; Run rate 8.70; Economy rate 8.58
Captain: Ryan ten Doeschate
Coach: Anthony McGrath
Overseas Players: Neil Wagner (NZ), Adam Zampa (Aus), Peter Siddle (Aus)
Essex, perpetually nearly men, had qualified from the group stages five times in a row until last season's blip and the addition to the coaching staff of Dimitri Mascarenhas, recently coach to the Melbourne Renegades, aims to recover that reputation. They also field a legspinner they have long yearned for - Australian Adam Zampa is available throughout. One fact not widely appreciated is that Varun Chopra was in the top three six hitters last season, quite a feat for an orthodox batsman not known for brutish strength. With their Championship defence misfiring, some raucous nights at Fortress Chelmsford could come at a good time.
One to watch: Zampa was described in one Australian newspaper as "a deep-thinking vegan warrior" which might come as a shock on a raucous Friday night at Fortress Chelmsford. His primary task is to take wickets in the middle overs and he comes with a wealth of T20 experience. Eager to prove his worth, he has been warming up with a month's club cricket in the Essex League for Brentwood.
In a word: Unfulfilled
bet365: 12
Glamorgan
T20 best: SF 2004, 2017
2017: SF; RR 8.82; ER 8.50
Captain: Colin Ingram
Coach: Robert Croft
Overseas Players: Usman Khawaja (Aus), Shaun Marsh (Aus)
Which Glamorgan are we about to see? Will it be the county which reached the semi-finals in 2017 and, powered by Colin Ingram, were championed as the most dangerous white-ball side in the county's history, or will it be the county that has had a nightmarish season in both Championship and 50-over cricket as efforts to build a team with a strong Welsh flavour have proved such a difficult challenge? Ingram's 59 sixes last season won recognition as the PCA's T20 Blast Player of the Year and attracted interest from Australia and Pakistan. Now captain and white-ball specialist, his task is to build a Glamorgan side in his own image.
One to watch: Andrew Salter has long regarded as a natural successor to Robert Croft, his county coach, as a run-making offspinner and some useful overs would be of great benefit to a Glamorgan side that convinces more in batting than bowling.
In a word:Yearning
bet365: 18
Gloucestershire
T20 best: BF 2007
2017: 9th, South Group; RR 7.53; ER 7.87
Captain: Michael Klinger
Coach: Richard Dawson
Overseas Players: Michael Klinger (Aus), Andrew Tye (Aus)
Michael Klinger retired entirely from first-class cricket in Australia earlier this year, but he has two more seasons as a T20 cricketer with Gloucestershire, where he has been one of the most productive and popular overseas cricketers of recent years. He faces a considerable task to rally a Gloucestershire side that finished bottom last year and which looks short on star quality. Ryan Higgins, a shrewd acquisition from Middlesex, has proved himself more than just a batsman who makes things happen by improving his medium-paced swing bowling so much that he finds himself top of the county's Championship averages: Gloucestershire need some exciting nights from him.
One to watch: Benny Howell is one of English cricket's most underrated T20 cricketers and that frustrates him so much that he even took to the pages of The Cricketer magazine to present himself as worthy of an international cap. Howell, who learned his change-ups by studying baseball pitchers, is likely again to prove himself one of the most skilful and economical T20 bowlers around.
In a word: Resourceful
bet365: 20
Hampshire
T20 best: Winners 2010, 2012
2017: SF; RR 8.44; ER 8.17
Captain: James Vince
Coach: Craig White
Overseas Players: Colin Munro (NZ), Mujeeb Ur Rahman (Afg), Dale Steyn (SA)
Hampshire have made seven Finals Day appearances, more than any other county, and disposed of Kent over 50 overs in the Royal London Cup final on Saturday. It would be no surprise to see them follow up with the Blast. The Ageas Bowl should fairly be bouncing, such is the talent on show. The replacement of George Bailey and Shahid Afridi with Colin Munro and Mujeeb Ur Rahman gives the squad a more youthful feel and Sam Northeast brings more vigour to the middle order. James Vince has been in dreamlike batting form since his England omission and Reece Topley is desperate to reassert himself with the ball. Mason Crane's fitness is a worry.
One to watch: Discovering how Afghan spinner Mujeeb Ur Rahman, only 17, copes with a summer of T20 in England will be one of the great delights. No spinner with more than 10 wickets had a better average at the IPL this year and his ability to bowl off and leg spin identifies him as the most exciting teenager around.
In a word: Eminent
bet365: 8
Kent Spitfires
T20 best: Winners 2007
2017: 6th South Group; RR 8.63; ER 8.88
Captain: Sam Billings
Coach: Matt Walker
Overseas Players: Adam Milne (NZ), Carlos Brathwaite (WI), Marcus Stoinis (AUS)
Canterbury is one of the sleepier T20 venues with indifferent advance ticket sales. They deserve a rush of enthusiasm because they have one of the most exciting batting line-ups in the country even without Northeast, who upped sticks to join Hampshire with a few sideswipes at what he regarded as old-fashioned committee ways. It has to be said that Kent have responded to his absence in positive fashion, on and off the field. The batting form of Heino Kuhn and Joe Denly swept Kent to the Royal London Cup final, and the skipper Sam Billings is back from IPL and England duties, but the seam attack is vulnerable and James Tredwell's long-term shoulder injury puts a lot of spin bowling responsibility on Imran Qayyum.
One to watch: Darren Stevens, at 42, fills every club cricketer with hope as they imagine if only they could match his guile and control then, at between 65 and 70mph, they to could become one of the stalwarts of the county circuit. Add his 3,128 runs at a strike rate of 141.92 and it is little wonder that Stevens is held in such regard. If this really is his final season, he deserves a great send-off on every ground he plays on.
In a word:Unbalanced
bet365: 16
Middlesex
T20 best: Winners 2008
2017: 7th South Group; RR 8.34; ER 8.41
Captain: Dawid Malan
Coach: Daniel Vettori
Overseas Players: Ashton Agar (Aus), Dwayne Bravo (WI)
Much was made last season about the recruitment of Daniel Vettori as coach and Brendon McCullum as part-time captain, but the outcome was much as ever as Middlesex, often disappointing in the decade since they won the trophy, finished seventh. Vettori, who has also overseen some modest seasons at Royal Challengers Bangalore, is back again, this time overseas recruitment consisting of Dwayne Bravo and an Australian version of Vettori himself, if somewhat less hirsute - Ashton Agar. Middlesex will hope to be in contention when Eoin Morgan returns from England duties: his record last season of one fifty in 14 goes (average below 23, strike rate below 130) lacked the inspiration Middlesex need from an England captain and questioned his ability to mentally attune to the county game.
One to watch: Ireland's uncomplicated strokemaker Paul Stirling had a brilliant 50-over competition, making three hundreds in eight innings and averaging 73.57 at strike rate of 89.25. His impact at the top of the order will be crucial.
In a word: Disappointing
bet365: 14
Somerset
T20 best: Winners 2005
2017: QF; RR 9.04; ER 8.75
Captain: Lewis Gregory
Coach: Andy Hurry
Overseas Players: Corey Anderson (NZ)
Somerset only field one overseas player and Corey Anderson, the New Zealand allrounder, is back to complete his "unfinished business" after his 2017 season was interrupted by a back injury while bowling his first over of the campaign, against Surrey at Kia Oval: he worked off his frustration by slamming 81 from 45 balls and managed four matches. Somerset's impressive young Championship skipper, Tom Abell, steps down for Lewis Gregory in T20 which is not ideal with Gregory's future still in doubt. Some high-scoring matches are in store at Taunton, but Somerset might be pushed to repeat last season's quarter-final. Legspinner Max Waller is a homegrown T20 specialist.
One to watch: Quite which of Somerset's young batsmen will get opportunities in the Blast is uncertain, but if George Bartlett finds himself on the team sheet ahead of Fin Tremouth and Tom Banton he will not be overawed. Bartlett, who struck the highest overseas score by an England U-19 batsman last year - 179 against India in Nagpur - has followed up this season with a maiden Championship hundred and has shown flashes of great promise as a top-order batsman.
In a word: Entertaining
bet365: 12
Surrey
T20 best: Winners 2003
2017: QF; RR 8.49; ER 8.65
Captain: Jade Dernbach
Coach: Michael Di Venuto
Overseas Players: Aaron Finch (Aus), Nic Maddinson (Aus)
Surrey should once again have bragging rights among the two London counties and packed crowds at Kia Oval should be rewarded with a last-eight place. The presence of Morne Morkel on a two-year Kolpak deal has allowed Surrey to major on two overseas batsmen: the Australians Aaron Finch and Nic Maddinson, who headed Sydney Sixers' run charts in last season's Big Bash. Youngster Will Jacks might also force his way in. Jade Dernbach, quite the trusted old pro these days, skippers an attack based on the two Curran brothers, England calls notwithstanding. Gareth Batty, overshadowed in the Championship these days by Amar Virdi, will be hankering for a scrap or two.
One to watch: Ollie Pope's invention created a favourable impression when he broke into Surrey's T20 side last summer and since then his reputation has leapt ahead with three centuries and an average of 93 in the Championship. England is drowning in talented batsman-keepers and Pope's exuberance has already won him a host of admirers.
In a word: Exhilarating
bet365: 7
Sussex Sharks
T20 best: Winners 2009
2017: 5th; RR 8.63; ER 8.31
Captain: Luke Wright
Coach: Jason Gillespie
Overseas Players: Rashid Khan (Afg), Tom Bruce (NZ)
No county possesses a more talented bowling attack than Sussex - indeed, if they all stay fit, fitting them all in the side might be the biggest challenge for the coach, Jason Gillespie. The IPL-tested trio of Jofra Archer, Chris Jordan and Tymal Mills, the parsimonious left-arm spin of Danny Briggs and the teenaged Afghan leg-break bowler Rashid Khan (who might limit opportunities for Will Beer) are just for starters. Sussex's major task will be to make enough runs which makes the New Zealander Tom Bruce, who replaces the injured Stiaan van Zyl, the most vital player of all in an XI that will need to bat deep and has the capacity to do so.
One to watch: Laurie Evans is likely to take over the top-order role that Chris Nash, now at Nottinghamshire, performed so successfully for many years. Evans topped the batting averages in the 50-over competition and he will also be crucial to Sussex's chances.
In a word: Panache
bet365: 7