any spot to check which pays best?
No ideally in the long run they should all pay about the same (assuming you are using one of the top 3 pools). What comes down to choosing the pool is fees, support, and reliability. ghash is 0% fees but can be a little glitchy at times. btcguild is pretty big and has great reliability but has fees. I could go on with other pools as well. BEst advice I can give is try a few and see which you like the best. It all comes down to personal preference.