Obviously a huge Gainax and Trigger fan, so much that it dominates my 'favorites' list below. However I don't feel it fully reflects my tastes, so I'll list more favorites here in no particular order.
Ping Pong the Animation
Kiki's Delivery Service, Whisper of the Heart, Wind Rises
Kobayashi-san Chi no Maid Dragon
Suzumiya Haruhi no Yuuutsu
Serial Experiments Lain
Girl's Revolution Utena (Revolutionary Girl Utena)
Panty and Stocking with Garterbelt
Plenty of other great anime that almost made this list that I need to rewatch. Typed this up real quick and haven't put much thought into it, it's a work in progress.