Rob 'Marion and Geoff' Brydon does loads and not neccessarily in his own voice (eg some Andrex puppy ads), so hard to pick out which ones. Andrew Lincoln (This Life, Teachers) and Hugh Laurie also do a fair few.
King of the voice overs used to be Ray Brooks (Robby Box in the TV series Box Clever) who was rumoured to earn over a million a year from syndicated voice overs - but he may have been superceeded by now.