I was looking at the Sharp 70 for a while (ultimately got the LG 65" because Sharp 70 was just too big for our living room). I knew there were different models, but not this many. Basically I got down to choosing between the 632 (cheapest), 735U(last years model with 3D and Quattron and Aquatron 240 refresh), and 734U(this years model with 3D but only 120 refresh).
Ultimately I would have gone with the 734U since its the best balance of price and features. The added yellow from the Quattron wasn't that big of a deal when I looked at it in a store, and never really saw any issue of having only 120Hz. And I like having 3D as an option. My LG has 3D, and is pretty good. Not much 3D content out there, but every once in a while a good looking movie comes out.