Judging by the type of anime your watching you should defenetly watch the Rurouni Kenshin - Reminiscence OVA "they don't call it the greatest anime ever for nothing" after that you can decide if you want to watch the tv series
You should also check out the new ninja anime out right now called Basilisk: Kouga Ninpou Chou, is very good so far.
Oh yeah and another of the great ones Berserk