well the top 15 I love enough to desire cels 
from:(Also those I recommend first for people 
who are not otaku yet)

1 Slayers/slayers movies
2 Tenshi ni narumon
3 Ping Pong club
4 Bastard!!
5 Master of Mosquiton(ova)
6 Fushigi Yuugi (tv)
7 Jubei chan
8 Neia under seven(cg I know)
9 Trigun
10 Serial experiments lain
11 Ranma 1/2
12 Cowboy bebop
13 Angel Sanctuary (cg too)
14 Saber marionette J
15 Haunted Junction

a couple not yet released that I loved:
love anime awa awa (i think)
because it has ebi-chan the housekeeping hamster 
(sick perverted and funny as heck)
Marmalade boy. (^_^)
VOH