One thing to keep in mind about the Delta cards is that they (accidentally?) removed the "independent" option from the latest driver release which is important for multi-channel playback on mAirList. M-Audio say they are aware of the problem and will re-add it, but for the moment, you need to manually install an older driver version in oder to make the cards work.
I have no personal experience with E-MU cards, but I know that several people are using them, without any major problems apparently.