I tried etherpool.org and minergate.com, and I got like 1.5 times more ETH from the etherpool. I'm not pretending to have conducted a scientific research on this topic, just an observation.
Etherpool awards you proportionally to your mining capacity, with minergate it was more like a casino, different pieces of work you submitted were worth more, some other - less.
Also, minergate is known for having some shady deals with Monero currency back in the times.
But you can basically go with any pool you like, make sure they have enough power to mine some blocks every now and then, so that you can get a piece of pie as well.