The T3i does not have continuous movie focusing like the other two, and as you know neither does the 60d. For ski edits, especially on bright days when you're stopping down the aperture a lot this doesn't matter as much as you have a greater depth of field, however, if you do think you need that auto focus (which is a nice feature) certainly go for the other ones, t4i/t5i. I have the 70d which is nice enough for what I need. And although there is not a large improvement in terms of image quality, the robust nature of the xxd series is very nice. Coupled with continuous auto focus in movie mode it's a great investment, especially when thinking about shallow DOF follow cams and such.
Also, no matter which cam you go for I highly recommend going refurbished. It's a great option for saving a few bucks and canon has deals going on all the time in their refurbished store.
Hope that helped man!
People helping people, its powerful stuff-AJizzle
ball bang is gnarly, but if you get it, you know you sent that shit to the thug zone and its worth a claim-shmad