Samurai X ovas (it’s really Rurouni Kenshin, but someone *edited*ed up in the US translation) there are only 4
Rurouni Kenshin you’ll know when it starts sucking around ep 70, you can stop if you want (nothing of value will be lost)
Read or Die ovas
Initial D is interesting if you like street racing and can get past sub-optimal animation at the beginning, Initial D 4th stage is awesome though if you are willing to get right into the show (i think you can do it, some characters come back, but their appearance is explained well enough that you don’t need to worry)
Beserk is fantastic
Big O season 1 is pretty awesome, the animators worked on Batman: The Animated Series, season 2 was fail though : (
Last Exile was pretty interesting, but i think the concept of the world appealed to me more that the series
Hajime No Ippo was awesome, it’s about this high school kid who takes up boxing, it’s really well done with a lot of heart
Slayers was pretty interesting, but it may have aged poorly
Vision of Escaflowne is older but it’s still very good
Hellsing has it’s moments
that’s about all the ones that i can think of that haven’t been mentioned already, i enjoyed the Gundam series, 008th MS team is awesome, and Bleach was good but since i couldn’t find some eps i quit.