I'm a Shimano guy for the moment, though SRAM stuff is pretty slick. For brifters: The Shimano lever functionality is nicest for me, and I prefer the wider hood than SRAM. The new Shimano lever design (6700) is really neat. It incorporates the best of all worlds, IMO, and shifts very smoothly. My only complaint with Shimano stuff is the saddle shape of the 5600, 4500 hoods, and the fact that the finish they use doesn't stand up to whatever chemicals are in some people's sweat.
For other components, aside from derailleurs, which have to along with the brifters, I'd go with Shimano. Their cranks are more cost effective. Their cassettes and chains run quieter, and their hubs are unparalleled (save for Phil Wood).
I find Campy stuff overrated, overpriced, and resistant to innovation. At one time they were king of quality, and I think they're still living in that era, before Shimano and SRAM stepped up their game. That isn't to say Campy stuff doesn't have benefits or fit preferences for many, but I think they could do much better.