They are in my top 5 - seen both the Marks a lot live, but never Stewart Lee (only TV and YouTube gigs).
I saw Mark Thomas (and spoke to him) a few months ago at a benefit for the Orgreave Truth And Justice Campaign. He's still got the fire and the wit! There was also a band there that I should have known but didn't - Ferocious Dog - a folk-punk band that has been about for 12 years and fronted by an ex striking miner from Nottinghamshire! I am now a convert and a fan!