As mentioned above, knowing your budget would help. I also will throw out the "shoot to need" comment. You've had the 60D for 5 years, where is it deficient? Do you find the IQ lacking? Do you want better performance at higher ISO? Do you want more AF points? What do you need that it does not provide?

In addition to a new camera body, you could consider new lenses, support, or lighting. For young children I could see a faster lens, and lighting for portraits and indoor photography. While I almost never post them, probably half my pictures are of my various nieces and nephews. Even with a 5DIII and 24-70 II, I often need a flash to get better lighting indoors. Dropping down to the 50 f/1.4 art can usually capture enough light but then I have an extremely thin DoF. So, really, the flash is the way to go.

My sister has the 60D. Looking through her images, my biggest issue wouldn't be the IQ out of it, but she shoots jpeg and does zero post processing. Do you shoot RAW? Do you have good post processing software? A good monitor (my current obsession)?

All that said, the 5DIV should not disappoint. I can see the 80D if you want better low ISO performance, more AF points or AF microadjust. Perhaps you will notice ~0.5 stop better high ISO performance. The 7DII if you want a very robust body and 10 fps, otherwise, I would go with the 80D.

Just understand that these are all tradeoffs. Part of me misses the portability of my first 7D and EFS 15-85. Great combo. I am very happy with a number of the images I took. The 5DIII and 24-70II combo gives better IQ, but is also much heavier and has a more limited focal length range often necessitating taking a second lens. That said, I wanted the better IQ, so I have not looked back.