You can't lose with the current selection.
It is a really interesting time for smart phones.
There are three major players in the smartphone world.
Apple iOS
Google Android
Palm webOS
We all know Apple and the iPhone. It's a great phone. Simple, top notch hardware, stupid fast and reliable. However, it is not the phone for everyone. Yes it has the most "apps" but there are a lot of shortcomings of iOS and Apple. Hardware diversity is terrible. Not everyone will love the glass screen, the 3.5" touch display (even though it is the most accurate), weak speakers, and new microSIM standard.
Google's Android has great hardware diversity. Google's Android has terrible app system because of it's hardware diversity. This is exactly the same problem Windows Mobile had. Granted Android is a great mobile system, but if you want to play games or use certain apps, forget about it. However, Android not quite "open" Operating System is the best when using Google services and doing simple things like...backing up the phone or accessing the file system.
Palm webOS is the latest and probably one of the most innovative mobile Operating System there is right now. Nothing can match its ergonomic use of their phone and software. You just have to use it and see the demos of Palm webOS devices. However, Palm was an independent company that had to skimp on things. Where they excelled in innovation and easy of use, they failed in marketing and hardware build. The devices aren't the best, however at their current prices, it's hard to beat. You can't lose on a webOS device but simple things like Soundhound, document editing, Camera apps are not there yet, but with HP buying Palm, 2011 is looking good as new hardware is coming and webOS 2.0 improves what is the best mobile operating system there is.
I can say that as a user of an iPhone 4, HTC Evo, Motorola Droid X, Samsung Epic 4G, Palm Pre Plus, and Palm Pixi Plus.
I have not had time with Windows Phone 7 devices, but I can tell you from experience from getting a Palm Pre that early adopting is exciting for hardcore geeks and not for the average user.
Choosing a smartphone now is getting harder and harder as CES 2011 is coming up and you have Apple's usual June announcement.
Just try out all the phone you can and try to come up with what you want.