I have the HTC Desire. It is an excellent phone, and in my opinion is as good as a iPhone 4 in ways. The decision for me to go for the Desire was that I refused to take out a mortgage to fund Apple's latest creation.
In all seriousness it is a very good phone, and I am more than happy with the Android software. The one downside is the Android Market is not as well populated with apps like the Appstore, and there is many apps that are of less than desired quality.
The Android platform is a strong competitor in the phone market now, and is well supported.
The main alternative is Apple, and as a previouse owner of the iPhone 3G. I can honestly say they are very good. The advantage would be they just work, and do everything they are designed to do well. All be it maybe a little restrictive at times.
If its a Android phone you want. The market has a huge variety, and please don't hesitate to contact me if you would like anymore help.