I don't think I can make a very good top 10, but some characters I've really like are:
Spike Spiegel (duh!)
Vash the Stampede
Nicholas D. Wolfwood
Goku
Vegeta
Piccolo
Monkey D. Luffy
Roronoa Zoro
Sanji
Mugen from Champloo
Jin from Champloo
That's 11. Haha oh well. Anyway, those are just guys I like, definitely not a definitive list. Probably not even all my favorites...