Not that it really matters at this point but the 77D and the 80D do not use the same image sensor. They are very similar but they are not the same. Canon is constantly working on improving their image sensors while trying to keep costs competitive. The image sensor in the 77D uses newer technology than was available when the 80D was introduced. The newer sensor technology coupled with the more advanced digic 7 processor and software make the 77D the better choice if going for better image quality alone. That plus cost also make the 77D quite attractive. But, the 77D is still the top of the line Rebel, not that there's anything wrong with that. The similarly in the image quality plus additional functionality very well may make the 80D the better choice. Me personally, I'm waiting for the 90D to hit the streets.

Many just don't realize what sports/action cameras are vs consumer cameras.
The Canon sports cameras not only have a Processor, but they have TWO of those same processors. The extra processor has been tweaked and dedicated to handle JUST the FOCUS system. Fast frame rate aside, If the camera can't handle very difficult and taxing focus situations, you WILL miss shots, simply because the camera is NOT capable of focusing the subject.
In the Canon line-up, only the 7D/1D series cameras have the dual processors and are fully weather sealed, which is why they cost more!!!
SS