Well I moved my H50 twice and the first time as5 was applied and my temps were approx the same within 1-2*c. Second time I used ceramique and my temps were about 1* cooler than original. The Corsair tm was pretty good.
The Corsair stock TIM is actually Shin-Etsu X23-7783D. It's the best paste-based TIM. (Indigo Xtreme is the best, period, but it's not a paste application.)
Fry's actually has it for $8, but looks like it's online only and not in-store. It's well worth it though.
I was using the stock Corsair paste until I had to move it. Then I used AS5 because I have a tube of it. I haven't noticed a huge difference either way.