We have been using Canon EOS 90D and 70D. However, 70D is outdated, and 90D is definitely getting tired. We are getting a new camera next school year as well, and I was considering Canon R6 Mark II and Sony Alpha 7 IV. Most likely going with Canon since we have a few Canon lenses already.
I agree that the 18-135mm lens is good (and light), but the 24-70, even though it has a smaller range and costs more, is just great for our needs and is being used 80% of the time. We are also getting a 70-200 with the new camera, and that is pretty exciting! :)
If the budget doesn’t allow for both, I would focus more on a better lens than the camera.