For me, I don't need my smartphone as a game pad, and I do need to read mail containing various Office document formats. These plus the fact that I get a developer license to write WinPhone Apps drives my decision to buy a WinPhone.
However, my mobile carrier only offer data usage tracking Apps for iPhone and Android, so I have to play safe and sign up for "unlimited usage" plan and that's about HKD50 more than the standard one. The government departments and lots of shops doesn't offer App for WinPhone so I don't have access to online Tax processing, query of government offered Wifi locations, etc. It'd take time for WinPhone to catch up for these areas.
EDIT: It's funny that a few sites of HK government still have the line "WinPhone version is available at Zune."