I have a Samsung Charge powered by Android and has 4G LTE.
So far I'm very impressed with the 4G LTE speeds. Its definitely fast from my point of view compared to 3GS. However I am annoyed that sometimes it crashes when switching between 3G and 4G. As for Android, it supports all the things the OP requested, but it has its own set of bugs. My phone crashes periodically and there are times I have to reboot it. I'm not sure if its the 4G that causes it to crash as most of the crashes happen when I am on the internet...but other than that, I'm very impressed with it and I also like the customization and widgets that come with it. Overall I think its a good investment even though battery life is pretty lame on this phone. Originally I thought about getting an Iphone, but my coworker hates it so much that he convinced me to get an Andriod. Both OS have their own sets of issues.