[Windows Phone 7 General] justinxtreme:
It's really a personal choice. It depends on which one you like better

Android feels (intentionally) unfinished in my opinion, so manufacturers can skin it. HTC Sense is a graet user interface in my opinion but you can't generally say that's the experience you will have with another Android device. Also their devices are inconsistent, some missing features including serious ones like hardware-accelerated graphics (on some phones like I think the Optimus T) which prevent users from playing games. Sometimes open is good but it can also be bad. It all depends on the manufacturer now. In my opinion I'd go with HTC devices, they're Android devices feel furnished, clean, fast, and simple. One problem I've had with Android devices is how the Android Marketplace doesn't have the apps I need or want, yes there are over 100,000 apps but if it's all app for the same exact thing well it's kind of pointless. The only quality game I've found at the Android Marketplace is Angry Birds. Also some apps are only device-specific. Updates for Android devices take really long to be officially released (although higher-end phones usually get updates a lot earlier) and lower-end devices running an older version of Android are usually promised with an update to the newest one but take so long (Motorola Backflip for example). Another thing is Android has multitasking but the official task manager really isn't that good (you have to go to Settings, Applications, select an app to stop) and the task managers at the Marketplace aren't that good. Still Android is an open system, allowing endless possibilities, like video calling and such. Official features are just the core, it's what the community can do with it that makes it special

On the other hand, with Windows Phone 7, Microsoft controls pretty much everything. When you use it, it will feel like a closed system, a lot more closed than Apple's iOS system. Bing Search, XBOX Live, and Office integration is nice. The search feature may seem useless but it's actually very useful, I usually use Google but find Bing to be a nice alternative especially considering how fast the Search feature loads. The games on Windows Phone 7 are alright, a lot of nice games but better ones are coming like Angry Birds and Traffic Rush. Also Windows Phone 7's Metro UI look really modern. Simple, clean, and extremely fast. Still there aren't as many apps in the Marketplace with only 5000 apps although considering how it was just released a month ago, that's a pretty fast pace. It may have to do with how the SDK is compatible with Windows. I also like the Music + Videos app it's very nice, Zune HD in your phone just like iPod in your iPhone. The downsides though include no multi-tasking, copy-and-paste, or video calling support yet. Another thing is apps like Facebook don't work well yet (although it does have integration with Facebook in the Peoples app). Multi-tasking and copy-and-paste support will come early next year and video calling depends on a front-facing camera which aren't on any current devices yet. Being closed, there's also not that many tweakable or changeable features in the operating system yet, although in my opinion I really don't wanna change anything (a wallpaper at the Start would be nice though). Just think of it like Palm's webOS, except Microsoft is trying a lot harder to make use of that potential.

It all comes down to, do you like open or closed, which user interfaces do you like, which apps do you use, and such.

You really can't go wrong with either one.