I've played on Rebirth and ED. Overall, Rebirth has the better server code and gameplay is better. The trouble with Rebirth was dev commitment and population. Lot's of people would not roll or leave due to the population. Even with that we had a pretty solid raiding group that was clearing all the content available (MC, ZG, World Dragons, Ony). We still had that group when freaky released BWL all messed up. That was the final blow for our raiding group. Quite a few of those folks have rerolled on ED and are doing fine. I don't like ED as much as I did Rebirth, but they are getting content out. BWL is open and mostly working on ED while Rebirth has been open longer and still hasn't gotten BWL out. If you want to PVP, ED is really your only option as it's population is considerably higher.