Go to the
Mining Pool List. Choose any pool that's listed as "ASIC Ready" on the right hand side. I've tried Ozcoin, Slush, Bitminter, Eclipse, BTCGuild, 50BTC, and a few other smaller ones.
I don't like adding to pools that are already too large, so I tend to stick with small/medium pools. 1-2 pools getting too large is not good for the network, IMO. For me, this means BTCGuild and 50BTC are out. I also don't think a pool can viably be run long term as PPS, again 50BTC is out. Then you have to evaluate your trust of the pool op. For me, this is almost more important. My personal opinion: Ozcoin and Slush are top knotch, with Bitminter and Eclipse as close seconds. I also trust eleuthria explicitly in this regard, but their pool is too big. EDIT: Well actually they're still less than 25%, which is better than the high 30s they used to be, so that's not as bad as I thought. Still, I'd rather encourage small/mid sized pools, and spread the hashrate out a bit.
I would also vote for balance if I could. You should be doing failover at the very LEAST! I'm gonna vote for Ozcoin, but I would also be voting for Slush if I could.