Which is better back-end mining pool? So far I've seen Pushpool, PoolServerJ and P2Pool. Which one of this would be easiest to set-up, maintain, effectiveness, and overall security?
PoolserverJ seems the best so far and easiest to set up.

Pushpool was the original but has some issues. The documentation is also a little hazy if you're a newbie to linux.

P2Pool is a decentralised pool, meaning that if you want to set up your own private pool, you can't use P2Pool.