Originally Posted by Matthew Vesey
I just bought a Rebel T3I for the purpose of Videos, Gym Photos, client photos. It has outstanding video quality. I can tell you that I am blown away by the T3I. I also could not say no to the price I got it for. Black Friday deal at a local shop had it reduced to $529. T4I is more expensive despite not really being much of an upgrade at all. My 0.02 is go with the T3I. I would look into a new lens potentially though. The stock one does the trick but there are better ones out there!
There is little to no difference in image quality between the T2i, 3i and 4i. In fact there is also little to no difference between those camera and the 7D as well as a negliable difference in video quality when compared with the much more expensive 5DmkII. If you put good glass on the front of any of those cameras you should be more than happy with the result. Only advantage would be the flip-out screen (or the control layout on 7D and 5DMkII, if you're used to old-school Canon dial location) on the 3i and 4i if you're shooting alot of video, specifically with a hand-held or shoulder mounted stabalizer of some sort.
*Fun Fact: The movie Silent House was shot entirely with a 5dMkII. As well as the final episode of the TV show House.