LJ.CorralesGoing from a t3i to either the 5D3 or 6D is like upgrading from a Subaru Outback to a Porsche or a Corvette. Much more complicated, more features, better performance. Something to consider.
Also, are you shooting professionally? If not it might be better to stick with something cheaper like a 7D2.
What lenses do you have? If they're all APS-C only lenses you'll have to go all out and buy full frame lenses. This will exceed your $2k limit buy another $1k-$2k.
For video, the 6D is garbage. The 5D3 is better, but definitely not the best compared to newer Sony cameras.
You may want to look at the Sony A6xxx series. The A6000, A6300, A6500 are all crop sensors, but provide much better video features than the 6D. Those are cheaper, and may allow for better quality lenses. You could also look at used A7's.
If you're buying used, make sure it's from a reputable source. Check to see if there's spots on the sensor, how many shutter clicks, etc. Google to find a full list of what to check when buying a used camera.
That's a lot, but if I didn't cover anything just ask. I'll be happy to help!
Thanks for the comment ! Currently have a 50mm 1.4 and a 70-200 f/4. I had the kit lens with the t3i but i don't have it anymore since I sold the camera with it. I'm not shooting professionally, it's amateur thing and just for fun for now, but planning to make a career in this.
Haven't really considered sony a6xxx series but it look really great! What makes the difference between a DSLR and a mirrorless camera? Also, what about lenses choice for the sony cameras? Are there adapters for my canon lenses or I should just sell them if I go with a sony camera ?
Currently thinking about renting some cameras just to try them, then see how I like them.