this one - i'm seeing between 22.8% - 53% CTR with a CPM around $6
this one is my close 2nd. Right now IM ctr for me is above 2% and per click revenue is in the range of $0.04.
Juicy has been mixed for me, kind of low on the banner cpc side although I still like them and they run whenever the other networks don't fill the ad space
Exo had rather low CPM for me, though they tend to have the highest CTR, their IM ad by far had the highest ctr
Eroads - haven't given them a proper run, yet
This is however all on US/CA/UK traffic only, with a little bit of French and German I think
you'll have to test some or all on a good chunk of traffic and make conclusions and go from there