PPS pools are expected to average lower payouts than PPLNS.

The biggest PPS pools are around 10% or a lot more fees at the moment.
Even the highest paying PPS pool is rewarding their miners less than expected on PPLNS,

There's no reason to mine on PPS - they have to charge higher fees to avoid the risk of the pool going broke.
PPLNS doesn't have this problem. Avoid PPS like the plague