At the risk of having things thrown at me, I would say Voyager had the most talented main cast. Beltran and Wang were the only weak links, and even they had more good days than bad. Ryan, Mulgrew, and Picardo were as good as any other three, and the rest were more than adequate.
I'd have to put TNG second. Even if I do think Stewart is kind of overrated as an actor.
Which puts DS9 at third.
I'm going to go hide now.