How many shows even have just one or the other? There's Team Rocket, and... I can't think of any others for sure. (Transformers? I haven't seen much of the show.)
Anyway, I support a central villain with a healthy backing of underlings, with a few others trying to get in on the game. However, I also prefer my minor villains to have at least a little depth in themselves and show up later - even taking the existence of supervillains and such for granted, it's reasonable to assume that there wouldn't be that many, but they could also be recurring threats. (For example, I've thought of various Birdman villains who could have been condensed together, and the show would have been better for it.)
Anyway, I support a central villain with a healthy backing of underlings, with a few others trying to get in on the game. However, I also prefer my minor villains to have at least a little depth in themselves and show up later - even taking the existence of supervillains and such for granted, it's reasonable to assume that there wouldn't be that many, but they could also be recurring threats. (For example, I've thought of various Birdman villains who could have been condensed together, and the show would have been better for it.)