Pick the one you feel would work better ergonomically and the one that shifts to YOUR preference. Some people like double tap, some people like the Campy tab shifting. I personally like being able to shift multiple gears BOTH ways, while SRAM you have to tap the shifter alot to move down the cassette. Not a huge difference, boils down to preference.

Theyre both good products. Its not like youre deciding on no-name Wal-mart components.