Hrmm...one favorite?
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Full Metal Alchemist was probably the best complete series I've seen.
Interesting characters & good story.
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Otherwise...
Cowboy Bebop was good, if far too short. (Who could forget Edward?)
Utawarerumono was decent. (the series, not the game) (Interesting characters, and some decent music. Suara has a nice voice.)
Code Geas seemed interesting...always kept missing episodes though.
Kashimashi was short, but cute.
Bleach (1st season) was decent, at least, when the stuffed animals weren't on parade.
Ranma 1/2 was a little cheezy, but enjoyable none-the-less.
Inuyasha was fun, if a little juvenile at times. Good music though, both the J-pop intro/exit songs as well as what was composed for the series. The English dub was good, but having taken a little Japanese, I always enjoyed the sub-title version more. (Kaze no Kizu!)