Tie between Last Exile, FLCL, Trigun, and Shin-Chan.
If I really like an anime, I buy the DVDs. So the fact that I bought, or plan to buy, DVDs of an anime I'd already seen on fansub may speak to its quality.
Noein was awesome. I'm re-watching it now on DVD.
Last Exile is also really great. The ending didn't impress me too much, so it's behind a few titles in my 'Favourites' list. The Limited Edition Box Set is still on my top shelf though.
I now own Everything Ghost In The Shell, since the SAC: Solid State Society movie came out a few weeks ago. I have the 2 'Ghost in the Shell' movies, both 'Stand Alone Complex' series (including the tin sets for 2nd gig), and I just got the 'SAC: SSS' movie last week. This is a great series...but still not at the top of my list.
At the top of my list is RahXephon. It's a brilliant series on its own, but I attribute this show as my 'breakout' anime--the one that showed me that anime was more than Pokemon and Dragonball Z.
Tied for 2nd place are 3 shows: Gankutsuou: The Count of Monte Cristo, The Twelve Kingdoms and Eureka 7 (starts slow, gets awesome. slow episodes are important foreshadowing). If one is getting tired of the standard anime stuff, or just doesn't see the appeal (like ReloadPsi), check out any of those 4 shows before you make up your mind.
Notable up-and-comers: The Melancholy of Haruhi Suzumiya (fun, random show with a few truly epic moments), Darker Than Black (Feels/sounds a lot like Cowboy Bebop (Yoko Kanno rox), though it's quite different and better) and Tengen Toppa Gurren-Lagann (this show is freaking awesome).
My favourites at the moment are Code Geass, Noein, Death Note and Voices of a Distant Star.
"Reality is that which,
when you stop believing in it,
doesn't go away".
Philip K. Dick
There are others that I like, of course, but Serial Experiments Lain is my favourite.
The original Vision of Escaflowne is just about perfect.
I also love Fruits Basket, KareKano, Wolf's Rain, Maison Ikkoku, Gasaraki, Vampire Princess Miyu (OVA), the orginal Tenchi Muyou, Laputa, and Princess Mononoke.
I like a lot of shows. But my favorites are definitely Tenchi, Hellsing, Elfen Lied, and Cowboy Bebop.
That's the way it goes, when you're down here with the rest of us.
Serial Experiments Lain! Paranoia Agent! Bleach! Fooly Cooly! Inuyasha! Chobits! Gravitation! Samurai Champloo! I can't name them all!
I really like Outlaw Star and the whole Tenchi series a lot.