Well, I guess I tend to lean more towards the
popular ones.  If I was forced to pick one, I
would say Esca.  I go through stages where I like
certain genres. I definitely like great animation,
good plot, and a cute anime girl never hurts. Here
goes:

Old School:
KOR
Miyu

More Recent:
Escaflowne TV  (Not a big fan of the Movie.)
Macross Plus
Cowboy Bebop
Evangelion
Tenchi OVA (cant believe no one said this one)
Lain

Recent:
Haibane Renmei
Chobits
Love Hina

If you were to ask my wife, without hesitation,
she would say Totoro.  If I see this movie one
more time I will go burn his forest down.  (Just
teasing.)

There are a million more.  I'm just a fan of anime
in general, but I can also name a few that I think
really blow.