I would probably avoid Cowboy Bebop, its style of storytelling and unappealing characters and characters that make you not really care for them makes it a pretty ungood story.
Anyway, Id suggest these three, I guess.
Guilty Crown - Good action, visuals, and music, really one of the lead anime of the decade and is pretty good. Definitely look into it for its special powers, visuals, and storytelling.
K - Possibly one of the most explosive and action intense new anime of the year and bound to be even bigger, excellent music, character designs, story, and world.
Angel Beats - Hilarious and emotional, and really memorable for its short run, check it out.
Also suggest Death Note like everyone else, and Naruto or Hunter x Hunter if you really want some long anime.