I have an HTC 8X and love it. My brother has the Nokia 920; my dad the HTC 8S.
Windows Phone 8 is a cracking bit of kit, and to be honest there's no real shortage of apps unless you love to have millions of the things installed. Facebook / Twitter integration is built right in, Outlook.com is better than Gmail (and that's as a 10 year long Gmail user), and the interface is so intuitive anyone can figure it out.
The Nokia gets more exclusive stuff, has a better camera, but is heavier. I reckon the best is actually the 8S, which doesn't have the high res screen but is beautifully made and seems to be the perfect size. And it has MicroSD expansion.
Stuff that's not so good? No notification centre (although it's rumoured to be coming this year), media and ring volumes aren't separate, and the back button behaves weirdly in the browser. People have whinged about battery life, but I charge mine every other day and have no issues. The iPhone 5 will need charging every night.
Android (even 4.2) feels unfinished in comparison.
My Windows Phone homescreen: