I have owned both the Touch and the Mogul (currently the Mogul) and I am in the process right now of waiting for my new Touch to arrive. It is totally a matter of preference with regard to the keyboard and WiFi. Now that the touch has a rom that will run GPS, that is no longer a valid argument. I personally rarely use my WiFi, so the last is a keyboard.
While it is not the same, there are plenty of software based keyboards that run great. I would recommend that you head to a local Sprint store and try them both out for yourself, to see which one best fits your needs.
Also, here is another thread with comparisons of these two phones...
http://forum.ppcgeeks.com/showthread.php?t=13692
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