Not all dubs are bad, no, but when given the choice between an English dub and the original Japanese subtitled (or any original language for any film), WhyTF would anyone go English dub?
Because VIC MIGNOGNA. That's why.
Also, watch The Wallflower in English. Seriously, Hanna Alcorn completely steals the whole show as Sunako, and Vic Mignogna, Chris Patton, Josh Grell, Jessica Boone, and Greg Ayres round out the cast amazingly.
Cowboy Bebop requires no explanation on my part. It's just awesome no matter what language you watch it in.
Also, Miyazaki's movies have an amazing track record of doing well with American celbrity voice actors. That tends not to work, yet somehow it often works with his films.