Have both-prefer iPhone; in two and a half words: Mac OS.
If the upcoming 2.0 s/w update indeed includes push email and true MS Exchange support, iPhone will seal the casket on RIM’s products for good (coupled with the 3G iPhone 2).
The virtual keyboard and ergonomics of the iPhone are on-point with technology and the direction portables are headed. Just look at all the competitors and fakes out there (Meizo M8 anyone?), and all of those DAPs out there emulating the look and feel of the iPhone.
I suspect the 2.5G version out now will take another price drop come June/July (when the 3G is released) and really making it ‘affordable’ to the masses…mark my words :)