I can't believe I didn't see Cowboy Bebop in anyone's list. Are you people mad? By the way, I know you said you wanted less than 50 episodes, but Fullmetal Alchemist is only 51 episodes, and you would be seriously missing out if you passed on it.
So yeah, I recommend:
Cowboy Bebop
Fullmetal Alchemist
Berserk
Gantz
Trigun
I don't believe I missed anything there. Also, if you haven't, watch Firefly. Not an anime, I know, but that certainly doesn't stop it from being the greatest television series ever. Plus, only 14 episodes long.