I know you said you arent a fan of multiple team guilds, but ill include our info anyway just in case … Im not sure what your experience was in other multiple team groups or how their teams were structured. Ours are essentially their own entities, each team has their own raid leader and their own leadership separate from other teams … It isnt like an A Team and a B Team type thing. Most of the teams have their own guilds, all part of a big community. We kinda like to compare them to franchises, the community has an overarching set of guidelines for raid teams to follow, but the teams are their own and they manage their rosters/raids as they see fit so long as it doesnt break the overall community rules … if that makes sense.
Anyway, we are a large community with 10+ raid teams at various levels of progress from Normal/Heroic only to Mythic Progression, chances are we have a team that meets your needs