The two that top my list everytime are Cowboy Bebop and Samurai Shamploo their simply brilliant, and ive just finished watching the first 50 episodes of Kenichi the mightiest disciple which i really enjoyed, lots of action and really funny the characters are good too especially the masters, my other favourites are:-

Afro Samurai - Superb
Claymore - Good
Berserk - good
Hellsing (not ultimate) - Amazing
Naruto + Shippuden - Brilliant but a little to long
One Piece - Brilliant and funny
Samurai Deeper Kyo - Good
Wolfs Rain - Good
Blood+ - Good
YuYu Hakusho - Good
Lupin 3rd - Brilliant its very funny and clever although a little dated it is very worthy
Rurouni Kenshin - Good

I know there are many i have missed but there are so many ive loved and suprisingly not many i didnt.

Let me know if u think u can improve upon this list, if possible i would like to watch more anime similar to bebop or shamploo, or anything were the characters grow stronger i love sci fi but do not enjoy the mecha side that much....thanks and God bless u Ghibli u the man