Ashran is neither the best nor the worst in the current ebg group. I would say currently IoC is the best and has a bigger chance for a come back. While wintergrasp is the worst because it favors the defenders too much and because of that causes huge amount of leavers due to the idea of getting farmed for hk for 20 minutes without anyway of winning.
Ashran can go both ways even tho it has been neutered and because of that no events going on like in WoD. But ashran is the wet dream of arena players i guess. Just a moshpit of people attacking eachother.