Mine has to be Gregg Wallace:

http://en.wikipedia.org/wiki/Gregg_Wallace

He is bloody brilliant in Masterchef. Some of the responses he gives when he can't decide who should be voted off are comedy cold. My favourite being when he got so stressed that he took off his glasses, rubbed his little round head, and croaked out the name "John!" I've watched that bit about 10 times now.