In Canvas Feature Ideas the top ten ideas submissions that are tagged with admin are currently:
What do you think are the top two feature ideas/bugs/weaknesses in Canvas from the perspective of admins.
#1 (More granular permissions for admins) would be my top pick, but that Idea was Archived. We were told that each permission change needed its own Idea Request. There are now 11 Ideas but none of them have received the 100 votes needed to make it to the next stage. Voting on them is still open until November 4th. The 11 Ideas (and their links) can be found the this Idea: More granular permissions for admins
My second choice would be #2.
#8 and #2 (in that order) for me. I would say #1, but as Susan pointed out it was archived due to being several "different" feature requests (but not really in my opinion).
5 and 7. I believe 2 has already been addressed; when I masquerade as a student who has been made inactive in a current course, I have no way to access that current course.