I just finished running a 3 year all-homebrew campaign in 5e, so let me chime in with my own post-campaign thoughts.
First, 5e is my favorite edition of D&D, starting back from Moldvay's Red Box Basic. That said, it's not my favorite D&D-like game, which is 13th Age by a lead designer of 3ed and the lead designer of 4e and written as a "love letter to D&D".
Second, I'm burnt out on running it. I just wanted my campaign to end these last few months. Compared to other systems I run it's a lot more DM prep to make things move smoothly. And I've found that I like systems where down beats/failure can occur with some regularity just like in stories and movies, but because of the punitive cost of character death in combat - which is one of the most common ways to overcome challenges - that's discouraged in a D&D context. Another part is that I have limited play time, and the number of combats per 24 hours needed in order to balance the classes against each other at higher levels is just not something I can provide. My next 5e campaign will absolutely use something like the Gritty Rest variant, or something quite different, to make rate of encounters per "long rest" be where I want it to be.
Third, while talking about being burnt out, I also mentioned my next campaign -- odd things to put together. It is the most popular game out there, and a common denominator for my play group. I'm pretty sure that my next long form campaign they will ask for more 5e. But I need a break from running it for a while. I'm still playing 5e in another group, so I'm not burnt out on the system completely.
Fourth, I am loathe to start a new campaign right before 2024 and the new books. I've had a campaign transition from 3ed to 3.5, and the thought of being the formative half year into a new campaign and someone wants to replace their character because of changes is not something I want to consider. This isn't really a postmortem comment as it is a pre-change comment, but does still apply to the concept of my next 5e campaign.
Fifth, while combat is expected with some regularity, the system doesn't give me tools for making each combat interesting and different. Most foes are sacks of HPs that do damage. Compare to 13th Age were so many foes, especially once you get to the amazing Bestiary and Bestiary II all have twists and things to differentiate the combats built in. I could convert, but (a) some of the tools they use to do this are foreign to D&D and would feel out of place (such as "on an even hit, do this as well"), but more importantly I've already talked about the prep being one of the things that burns me out with it.
Sixth, I've retreaded the same lower levels so many times. But considering some of my players, I worry that starting at high level will end up with characters that don't have party or self synergy. And I'm not sure that the higher prep needed will be rewarding for me. So I don't know what levels I want to run next, but I know what levels I don't and it's pretty comprehensive.
Seventh, wow, this is getting long, anyway Seventh: I love worldbuilding, and I have a whole bunch of ideas I want to flesh out for unique settings and tales that can unfold in them that are enhanced/created by the traits of the various settings. And this is almost exclusively D&D high fantasy, created with the concepts of D&D in mind. So I'm going to return of my own free will at some point to a D&D-like. And considering my current player base it's much more likely to be 5e or 2024, not Pathfinder, 13th Age 2nd, or other D&D-like game.
Eight, but for the short term, I've got one of my players (whom runs a 5e game I play in) offering to run, but either 5e or equally crunchy games like Star Wars 5e or Cyberpunk RED, or I'll run something that uses different GM and creativity muscles, like a PbtA game - I've already proposed Urban Shadows, Masks: A New Generation, and Monster of the Week.