The results are in! The winner is CleverMining!

CleverMining	0,0429
WafflePool	0,0423
Hashcows	0,0327
Hashbros	0,0306
CoinSolver	0,0262
MiddleCoin Amsterdam	0,0223

It was a close call between CleverMining and WafflePool, they gave me practically the same results. However, CleverMining has a high reject rate (10-30%), with closer servers coming in the future I expect higher payouts. MiddleCoin admitted they had problems with stats and founding blocks, so their result may not be representative over the long term, as said earlier they gave me the highest payout before. Unfortunately, Hashbros announced they will shut down soon - so they don't really count anymore. And for some reason I can't find my results for the MiddleCoin EU mining.

tl;dr: Mine on CleverMining or Wafflepool