I started with bitcoinpool.  I got tired of idle miners.
I played around with some of the other pools, slush, etc.  Didn't seem to provide enough info/data for me to know how I was doing.
Went to deepbit.   No idling miners (so far), lots of data available to judge progress, etc.

People want minimum drama and results for their efforts.  The security threat people are talking about is below 50% anyways, so it just sounds like jealousy to me at the worst, anti-free choice at best.