I think virtually all superheroes with lots of story and history and supporting cast and villains would be ideal in a weekly serialized format. Even just 12 eps a year would be awesome, and saving the movies for team ups and such could be really really cool to me. Alas, there are *some* heroes who don't fare well visually on TV due to the budget. Though that number is shrinking as the gap between TV and movies shrinks (both financially and otherwise), there are still some that wouldn't quite work.
Spider-Man and the X-Men come to mind as characters whose stories are MUUUUUCH better suited to tv style storytelling than film, but who have some heroes and villains who just don't quite sing on TV the way they can on film. Spidey himself can't do web swinging the way we know and love without the movies and a few of the X-Men become unwieldly on TV budgets. That's a bit closer as there are so many characters you can flub and shoot around some of the more difficult aspects to visualize. There's certainly nothing in the 2000 X-Men film that can't be done on TV with high quality.
I think Batman would be insanely cool on TV, and while he may not have everyhting he does in the films on TV, he'd still have all the important stuff for Batman, ie, detective work, gadgets, martial arts, cars, badarseness. Batman is soooo good for TV that they made a Batman show using Green Arrow and it was still awesome, at least in season 1. Batman is so good for TV they could make a Nightwing or heck, a Robin TV show and it still be awesome. Batman is so good for TV, they can make a Batman show without Batman and just have a young Commissioner Gordon dealing with his enemies, and still be awesome. You almost can't go wrong with Batman on TV.