I control 2. Always control my Red Sox and an NL team (usually a rebuilding project), as I like the game management of an NL game better. I've run two franchises, one with the Nats and Sox that got erased (by this dummy right here

) and another Astros/Sox one, where I'm slowly building the Astros roster and playing as the Sox.
I figure once I've got the Astros in better shape (or with more players I like) then I'll control them more and try to get things turned around. I love the challenge of rebuilding a team over time.