We have tried:
Ghash - nice interface, but did not like what I researched about them or their policies and did not want to continue doing business there. Stayed about 12 hours, then switched.
Slush's pool - had some connectivity issues every so often, would switch to backups every so often, but fine otherwise. Smaller pool hashrate meant bigger swings in block times.
Bitminter - same as slush's pool.
BTCGuild - nice interface, liked mining there, no real issues if you want a decent sized proprietary pool to join. Mined the longest there so far (about a month), but recently switched to P2Pool.
We're currently running in P2Pool for almost a week, and I think we will stay with that. Looking into setting up our own node as well within the next month to participate in the network.
With the larger pools you get smaller payouts, more consistently, since they can usually find blocks quicker but they have so many people hashing. With the smaller pools you can go a day or more and find no blocks, then find 2 or three. It's a roller coaster ride.
With P2Pool you find and connect to a local node which is part of the larger network. It is decentralized, and I think more true to the spirit of bitcoin, where everyone is contributing to the network and you have no central authority controlling the pool. Fees are usually nil or very very low (.5% or less). Right now the pool hashrate is about 1Ph/s, which is small and recently we went almost 2 days without a solved block. Then, three in the past day. But, so far the payouts are no worse than BTCGuild over the week, and possibly better by a little on average. Also like the instant (well, after all confirmations clear) payout right to your address. No one else is holding our BTC, which could become an issue for the larger pools if the proposed NY State legislation goes through as-is.
My suggestion would be to mine with one of the larger pools (but NOT ghash) for right now to get a feel for mining. Do some research, know what your payouts will end up being over some time, and then possibly look into P2Pool. Read up around the P2Pool thread, lots of good info over there.
thanks for your answer but if i want to join in a p2pool how can i connect to one? is like the others pools, just use their server and putt them on the miner, or is harder than that? and do you think someday p2pool when she hits more hashrate, she will give better profits or is it proportional?