I always like to have a mobile that is different or has something extra ..my list from 2003 until now:

1. O2 XDA (Window mobile when it was revolutionary)
2. NEC 400i I-mode (first camera phone, i-mode was nice)
3. Nokia 6680 (Symbian was still good; unsigned apps, great 1.3 MP camera)
4. G-Cam Gigabyte (probably my best low-light camera ever)
5. I-mobile 902 (so so)
6. Samsung G810 (3x optical zoom, GPS)
7. Nokia N900 (best community, keyboard)

Next phone: not in a rush, but if anyone would get the Dell streak running on Maemo, it could be a candidate