I love Golgari, especially with Varolz,
Lotleth Troll in the deck. The problem I find is that it's a guild that doesn't really inhibit your opponent very much from playing his game the way he wants. It's mainly about boosting one of your own creatures up with scavenge until it's huge. But seasoned players will just throw counter and removal spells your way and then you're screwed. That's why I think it's not very suitable for competitions.