Hey, about the 60D vs 70D vs 80D question.
The 60D is an old camera.
Think along the lines of computers, cell phones, ect. The 60D came out when digic 4 processors were still current.
There have been several processor upgrades since then.
Digic 5, Digic 5+, Digic 6.
The processor is what the camera uses to generate the end image.
The sensor interacts with the light waves to turn create electronic information, but the processor is where the information gets turned into the end result.
Cell phone cameras are all about the processor, the brain, the software, the transforming of information into an image. Cell phone cameras 15 years ago are not what cell phone cameras are today. Thats due to advancement in processors.
The lenses are still tiny, the sensors are small, and would never be useful without the serious advancement in processor technology.
So, think about it that way.
the digic 4 processor that is in the 60D came out in 2008.
The 60D is still sold with the digic 4 processor even though there have been several upgrades since then.
The 70D is using digic 5+
The 80D has the latest and greatest processor, digic 6, that technology will improve your photos.
Plus, your camera is limited to how fast it can perform by how long the processor takes to di its job. Newer processors are typically faster than older ones. One of technology's improvements.
One other thing that has changed is the auto focus systems.
The 70D and the 80D have the new dual pixel auto focus system, the 60D does not.
All are aps - c size sensors, so that is equal. All have the same lens mount.
As one of the others said, the 80D has better video with the option to shoot at 60 frames per second in one of the 1080P modes, the 70 and 60 are limited to 30 Frames per second.
The 70 and 80 should have a larger ISO range than the 60. The increments should be better.
The 60D has better increments than the rebel cameras like the T5i and T6i, but the 80D should have a much better range.