T3i and T2i are same sensor. The major difference in the T3i is the articulating screen, some additional options for video... Really? the T2i is essentially the same camera and can save you a couple hundred bucks. I wouldn't buy the T3. It's the basest of Canon's entry cam's.
You have a more professional minded goal, don't you? I'd really suggest looking to the 60D or 7D if that is the case. if money is the problem, the T2i will serve you very well from learning through beginning your professional work. Investing in good lenses is most important of all