Used Limited because the cost differential narrows when you buy used. I am really enjoying all the luxuries that I have never had before. Then again, my last car didn't even have power windows or locks, so the SR5 would have seemed luxurious as well. In my opinion, you can't go wrong with any of them.
However, as far as new, the Sport does seem to be a great value, for the reasons listed in previous posts from all the sport owners. Especially, because you can get it with same color fenders.....which I didn't realize when I bought mine a month ago.
BTW, my girlfriend is really loving the Dual Climate control and I suspect in the winter she will be loving the heated seats.