Another user with a divided household... I'd have to pry my wife's Iphone from her cold, dead hands, and I'm having a hard time getting away from WinMo permanently. Besides my current WinMo phone (Palm Treo Pro), I have an Iphone and have experience with several Symbian devices, Blackberries, and even (gasp) PalmOS devices. There are things I love about the other platforms, but I just keep coming back to Windows Mobile. In it's current state, there's nothing thrilling about it, but it just works for what I need.
My primary requirement at the moment is flawless Outlook sync. Since I don't have a corporate phone at the moment, and since my company would sooner execute minions than allow them to connect personal phones to the corporate Exchange environment, I need desktop sync. I found the Iphone quite useful (and much more fun) on a daily basis, but the Itunes sync process absolutely destroyed my corporate exchange calendar not once, but twice, and I swear it'll never happen again. None of the other platforms handle recurring appointments natively the way that the Activesync/WMDC + mobile Outlook combo does. The Itunes sync actually caused recurring appointments sent by others to skew by a couple of hours while still showing the correct time on the Iphone (and yes, I checked my time zone config AND everything else). In the end, there was no solution but to restore my own appointments and have everyone else resend theirs, which was embarrassing to say the least. While not as drastic on the other platforms, I found that the Nokia suite, Palm Desktop, and the BB Desktop Sync all had their own set of issues while the WinMo solution kept on chugging.
Add the above to the fact that I can pretty much do whatever I want with any of my Windows Mobile devices. No draconian carrier or vendor restrictions, vibrant 3rd-party dev/hack communities (i.e.- XDA devs), free unlock solutions... If I don't like it, I can change it. With the exception of Android devices, which are really just now starting to come into their own, no other major platform offers that flexibility. It got really old having to "break the rules" on my iphone just to change my homescreen, springboard, or to do something simple like add thumbnails to my contact list view. Argh... makes me mad just thinking about it! I'll end my rant now, but while I love to toy with other platforms, I'll be sticking with WinMo for now and am hoping for big things out of WM7!