Katekyō Hitman Reborn! : It has about 203 episodes (at 133 myself :P) and it's fun to watch.
A big warning is that it starts really slow hence a lot of people stop watching it soon. The anime kicks off with the actual purpose around episode 30-40. It it is like Bleach in a lot of ways, though the main characters are 10 times more interesting then let's say Chad or Inoue if you ever watched Bleach. :P
But if you don't like Bleach then you won't like Reborn either as the story telling and combat is similar...
I'm with the other guy and wait...though I doubt I'l find it as cool as everybody says it is. I haven't actually heard a lot of decent arguments to why it is good next to "it's badass"...then again I never bothered asking those people for more info as they usually just watch anime for flashy clips.