Also got a Archangel Gabriel yesterday, don't know if that's a good monster ?
I may try one or two more roll in the REM during that godfest, don't know yet..
Hmm.
Well.
You're in the right place to be asking that question. I am, as far as I know, the only person in the NA server (and maybe the world, although I haven't looked hard elsewhere) who mains Gabriel.
That's a complicated question, but I'll try to give a simple answer. As a sub, absolutely he's great. Blue row teams love this guy. As a leader, I'm certainly biased but I truly believe he's the most underrated lead in the game. He's by no means perfect, but he is amazing and you can beat a vast majority of the game with him, including some endgame content, maybe even most of it.
Gabriel is slow, but he's EXTREMELY durable. Gabriel teams have absutely massive HP and recovery. Normally Gabriel's damage is extremely poor to compensate, but he has a secret weapon:
This guy's unorthodox active and leader skill let Gabriel change from a nigh-indestructie tank team to a burst team capable of one-shot killing a vast, vast majotity of bosses in the entire game with the right (fairly easy) setup. And you can just get Beyzul for free from a particular midgame dungeon, so if you have Gabriel you have the basic components of this team available to you already.
Once upon a time Gabriel teams were extremely hard to build because most of his good subs were exclusive to the rare egg machine, but due to some new monsters being introduced and some changes to Gabe himself you can now build what I believe to be a solid team with only free, or common rare egg machine, monsters with Gabriel being the rarest piece. It won't be optimal, but I think it should totally work.
Plus he grows up to be the most beautiful man in PAD, bar none. So there's that.