I use 2 Nikon 850’s. I keep an 80-400 or a second gen Tamron 150-600 on one. This is primarily for Wildlife. Should I end up finding a subject closer than usual, I will use the other, more sharp 80-200. I am satisfied with my larger lenses tho the Tamron requires skills similar to those a sniper might use in order
to get as sharp a picture as I wish.
The 80-200 2.8 is always just that little bit better and, of course, easier to use. Shooting birds and the like usually require very long lenses, but here on the Eastern Shore of Maryland I have Blackwater and Chincoteague/
Assateague where the wildlife are so used to people that they will sometimes remain fairly close. Rarely, however do they permit one to set up there tripod.
This works well for me. On travel, I might use a wide angle on one camera and a short telephoto on the other. Obviously, there are many other combinations available.
I like having not to think too much or too often so prefer 2 similar or same cameras. I can take a mint F3 along if shooting b+w or trying film.
That is my 2 cents worth.