Here's why I luv ckpool:

small pool, so payouts are bigger per input, making me save tx fees
FREE!
ck limits 5kb payout, other pools have something huge like 30kb+ payout which is a waste since these extra kbs were going to be transactions with fees (ck, you might consider reducing that to 2.5kb in the future as transaction fees get more and more important with time)
coinbase payment

As long as we stay >5p I will be mining here