Having used both my iPhone and the Xperia X10, I'd go for the iPhone.
The X10 is classic Sony Ericsson: good hardware, bad software. It's fast, it has a large screen and it comes with a solid camera, but most of the custom software isn't well-executed. Timescape and Mediascape are fairly clunky, and the on-screen keyboard is worse than what Google offers. You can remove or replace a lot of this (using custom software if needed), but then you didn't really need the X10 if so!
If you really want Android on Rogers, see how the Acer Liquid e fares. It should be frill-free. But Apple has a knack for a clean interface and a big app catalog.