I'm going to throw my opinion in here because I find a few real pain points that drove me to Android eventually:
1. If someone sends me a document or a file or something and I need to do something with it and send it back, it's hopeless. There isn't enough of a filesystem to do that sort of stuff with it. The whole WP isolated storage thing is painful and really ruins it for me. Not only that if someone sends me a media file or I download an mp3 for example I can only see it within scope of the app that received it and never can I add it to my music library without connecting it to a PC. I can't even play it without blocking the entire phone UI.
2. I really don't want to have to sign in at all and/or activate my phone as a developer device to deploy any apps or even a simple one shot custom app I've written for my own use. Occasionally, historically with WM6.5 and predecessors I've built the odd diagnostic tool that sits on the device. I can do the same in HTML on a web server somewhere but that relies on a network connection to be there, which even though I live in London isn't always the case. In fact it's pretty terrible in the suburbs. On basic GPRS WP is heading towards useless.
3. Android USB OTG is awesome. I can move stuff between USB sticks, plug keyboards in and all sorts. This has got me out of the crap a few times already and I've only had an Android handset for about a month now. The cable that enabled all this cost me (including delivery) £0.73.
4. Nokia made awesome hardware. Not joking it was the best stuff out there. Since the Lumia 820 though, it's turned to crap. I have repaired a number of handsets and they aren't designed with durability in mind any more and the parts are quite difficult to get hold of unless you're Nokia authorised service. Fortunately they still use standard screws (Torx TX4/5) but when you get inside, it's problematic.