Think my favorite anime would be a toss up between Cowboy Bebop and Trigun. The live action reboot of Cowboy Bebop was rather disappointing though. Outlaw Star was another good anime.
If you liked Trigun don't watch the remake Trigun Stampede which comes out sometime this month. The director of the remake has been bragging about how he was inspired by the Marvel Cinematic Universe instead of the Trigun source material
@AgentofSMC Thanks for heads up on that one.