In regards to what Comp112 said, I did notice one or two hiccups with my Focus when it first came out but I didn't really think twice about it since it did just launch. Any brand new OS/Phone is going to have a few problems. The only ones I really remember was maybe about twice the marketplace locked up and I had to restart my phone to be able to launch the marketplace again. But Like I said since the updates I haven't notice any problems tbh.
I think it comes down to whether you really need just those couple of apps that haven't been developed for WP7 yet. Because so many websites now a days have mobile versions I really haven't noticed the lack of flash support myself, but I'm sure some people notice it that stray from "mainstream" websites.
Not trying to sound like a fanboy here, but just saying if you can live without some of those apps that WP7 doesn't have yet I don't think you will be disappointed. If anything I might end up buying a cheap iPod touch to fill in the gap of the two or three apps that I really do want, but thats another piece of hardware. Let us know what you end up choosing!
Oh and AT&T is really slow on pushing out updates! That is one thing that really does bother me, but I guess it's better for the end user that the updates are thoroughly tested. And forgot to mention a quick note about email. Not sure if you intend on checking several different email accounts, and I don't have experience with how other phones handle it but I love the way WP7 handles it. It's very easy to set up several accounts imo, and since my school email uses Outlook web access it was a cinch to set it up. That was definitely a big advantage to me as well.
There's certain apps that aren't "dire" for me, I can watch Crunchyroll anime online with my PC, but being able to watch it on my phone while I'm out is convenient, but not a deal breaker.
I have a couple different iPods I can use for music, so that's not a big issue. I bought a 32gb iPhone 4 because I planned to use it as my music player as well, but over all there isn't a big issue.
I'll definitely let you know, but it'll be a month. I will update this thread, or I'll make a new one and link back to this thread and I'll even post pictures of the device I picked. I'll explain why I picked it, etc.
I can tell you this much, I am in the middle once again in terms of what to pick haha.