I think that if you describe "best" as "can get the most hours in the shortest amount of time" then you'll have really three-four choices, from my perspective. Trill, BFM, The ABB, or Voxel. But if you describe "best" as "having the most skilled members and refusing to noob recruit" than the question is more interesting. How do you measure the skill of players in a guild you weren't in/around for? Spar is a terrible indicator, since tons of people boosted way back. I myself can't judge really any guild before 2012. I would have to think for awhile to come up with a solid answer I was comfortable defending.
But for right now, I would say TaKaii. Though they aren't getting the most hours, they are also past 1k by a long ways. I won't say House is trash, they aren't. But they very often lack skill. They have 5-6 players with real skill, from my perspective. TaKaii has more then that. Though House is nearly done, so if your looking for a 1k guild they aren't for you. I would say either Sinners or Blood Drunk 2.