LTE vs. WiMax
1. LTE is
testing around 40Mbps down, 5Mbps up.
2. WiMax uses 2.5Ghz spectrum, LTE will use 1900mhz and 800mhz spectrum. The low-end spectrum is better at penetrating buildings and obstacles. If you're having problems getting WiMax in some zones you may have better luck with the LTE.
Other concerns
Would you rather have a large, bright screen or a battery that lasts more than 1 day?
Are you o.k. with touchscreen typing, or would you prefer a hardware keyboard?
Do you have radio-free zones in your house or workplace where you can't get a signal or often drop calls?
Do you travel outside of the US?
Do you want the best phone and price is no object, or would you prefer a great phone at a good price?
Do you want a phone today, or are you willing to wait for certain features?
If you're willing to wait, how long?
The main problems with the iPhones is that they're 3G-only and very locked down. Many parts of the country are reporting pathetic data rates on 3G right now. Some folks aren't comfortable jailbreaking their iPhone which you often need to do before you can do the fun stuff (Cydia apps, tethering, etc.).