If you saw Champloo and Chaos;Head, then Cowboy Bebop and Steins;Gate are absolute musts, without exception. I'll also second all the Black Lagoon posts and throw in FLCL for the hell of it. lol
All four have dubs and they're all some of the best dubs out there
one anime, to beat EVERY OTHER ANIME IN FEELS!!! idk if its too much for you, but its 50 episodes, and OMG!!! this is THE FACE of feels for anime... its available in dubb too!