My first ever anime i downloaded was Hellsing and i really enjoyed it and was hooked on anime after this.
My Personal best list would be :
One Piece ( Although i watch Naruto and Bleach for some wierd reason i dont like them dunno why t.t)
Others that i like but not great as above:
Neon Genesis Evangelion
Detroit Metal City
Hajime no Ippo
Ok for end I would like to recommend one great OVA series that just watched it today.
Rorouni Kenshin OVA( Or Samurai X : Trust and Betrayal )
This just blowed me away compared to the original series which i tried to watch but stoped at episode 10 or so cuz was too boring for me and too much childlish. This goes definately to my top anime list.
Definately a must watch even if you dont like the original series like myself.