As far as actual stand ups go, Kevin Bridges atm is my favourite by a margin. It's partly because I can associate with half the shit he says, but he's clever and his delivery is just phenomenal.
Reg D Hunter is brilliant. After the first time of watching him I got the impression he'd get repetitive after a few viewings, but I've watched a few of his stand ups and seen him on Have I Got News For You numerous times now, and he still has me rolling. ('To conquer Fritzl, you must become Fritzl')
As far as panel shows go David Mitchell is the funniest for me. His rants are just hilarious.