Need a camera for taking pics of my son (now 2 years old and starting to run around a lot) and family/friends. First camera I owned was a T2i and then moved on to a 5D Classic and fell in trap of the image quality out of FF . Then gave that away to a friend and got a 5D II. I have lost 5D II to a personal emergency. And now that it is behind me, I have some cash to invest on a camera. My lenses (which I kept) are 50 MM STM and 85 MM f1.8. My budget is in and around 600$ (used cameras) for the camera.
My primary goal is to get highest possible image quality within my budget. I am not sure if the focusing system of my 5D/5DII would be good enough for fast moving kids. I did my research and narrowed it down to 5DII, 7D, 70D and 1D Mark III.
I would need someone knowledgeable enough to give me some solid advise on what I should be buying for this. I can even sell my lenses to go for a different lens camera combo.
Any possible help is appreciated.