I'm not a complete fan of Ents either. I tried them in quite some decks, but most of the time they just slow me down. They have very decent stats of course, but during a round I can only use one of them (most of the times) and for every function there are equally good alternatives but they can be used during the round they enter play, and most of the time they have a side-effect as well. Another reason for me to not be that fond of Ents is the length of a game, since most games only take 5-8 rounds.
The only ent I do like is Treebeard. Since he gets that extra action every 2 rounds, which makes him a very solid defender and attacker in many games. and some readying effects (Ever Vigilant, Spare Hood and Cloak, Brand, ...) make him even more useful.
Scores to me:
Treebeard: 9/10
Wandering Ent: 6/10
Booming Ent: 5/10