Cowboy Bebop is what kicked it off for me. Outlaw Star was a lot of fun, but coulda used more cowboy style shit on the soundtrack. Watching Space Dandy now and while it's not quite a space western, it's pretty fun to me.
Anything else I should check out?
Watched it for the first time last year and really liked it a lot. I would say it holded up pretty well. I still have to watch the movie and Stampede tho.