Anyone without a fee. I'm not going to say that MY pool (Bitcoins.lc) is the best.
We're however the nicest one.
Don't go to deepbit or slush, use some other pool that doesn't steal from you.
Although as I said I prefer BTCGuild for it's fee freeness, it is just wrong to suggest Tycho or slush are stealing from you both seem to be great people that IMO react faster to outages, seem more stable, and initiate new features faster then the free pools. They both are very forth coming with their fees so how the hell are they stealing? Whether the fee is worth it to miners is their choice. I've use a bunch of pools and I've switched from fee free pools back to both slush and Tycho after problems with downtime, I've found that BTCguild is the best combination of fees and performance.