Nokia 3660
Sony-Ericsson w810i (modded with the K810's sliding camera cover)
Sony-Ericsson p1i (died in a tragic girlfriend-put-pants-in-wash death)
HTC Hermes (flashed to winmo 6.1 for threaded SMS)
Openmoko Freerunner (never used as a main phone, for obvious reasons)
T-Mobile G1
Nokia N900

I would say the N900 is my all-time favorite. It's got the right amount of openness and prowess. Runners up are the G1 and the P1i.