Should i get a windows phone 7 or an iphone 4?

So im in love with the fact that the wp7 works with and is like the zune. And the wp7 phones are gorgeous..lol, but the iphones are really cool too because of the apps and the webcam(my mom want to be able to see me over the phone...ewww).But i just want a really good device that can replace my crappy phone,and my dead zune. Any ideas??