Again, personal preference. I find the SRAMs to be much more ergonomic than Shimano, and the ability to shift while fully gripping the drops, using just tiny flicks of a single knuckle is a worthwhile improvement in my book. And, because I can pull the shifting paddle in toward the bar, I'm noticing that my hands are leaving the handlebars much less frequently than with the Shimano system, so overall, I'm in better control of my bike.

I can't speak to Campy.