The ONLY smartphone OS worth going with is Android. It's a million miles ahead of everything else.
Google have said there will be something like 12 more Android devices on the market by the end of the year, but the one I'm really excited about is the HTC Hero. That and the HTC Lancaster (also running Android) are both being announced officially on June 24th at a press conference in London.
Also, you've got the Samsung Galaxy coming out in a couple of months. My cousin is going to get one of those. It runs Android, has a 5MP camera with OLED hardware flash, 80GB of internal storage and a 3.5mm headphone jack (unlike all the HTC Android devices). It is supposed to be a beast of a phone.
I respect what Palm are trying to do with their webOS, but i fear it's too little, too late. And the current "Pre" hardware is horrible.
As for the XPERIAX2, masta, seriously? I mean the spec are nice, butWindows Mobile is the biggest piece of shit operating system I've ever had the misfortune of using. It's just a horrible, clunky, OS.
Flip, if you're looking for a phone right now get yourself a G1 on Rogers, or a Magic if a physical keyboard isn't a requirement for you. Either that or wait a few months for another Android phone to get picked up by a Canadian carrier.