For SHA256 I'd go for this:
1. Nicehash (with minimum payout to the "average" payout on 1 Th in BTC * 1,05)
2. GHash.io
Can we please stay away from Ghash for Sha though? Let's not allow them to get near 50% of the network again.
You're joking right? I think we are well past any chance of that happening again so easily... sitting close to 200 PH on the network now... and Ghash hasn't surpassed 56 PH with current nearer 46 PH... they have not been more than 30% of nethash in the last few weeks and it would take them 40+ PH from where they sit now to achieve that. I would be more worried at how quickly Discus Fish has grown and why none of the other pools can match CEX's success with Ghash.io's output.
It will happen again for sure, if people keep thinking like you do (it's ok for me to do it because the majority of the other miners probably won't!)
30% is, imho, way too big for something that's supposed to be decentralized.
Anyways, that's not what this topic is about, sorry for the digression.