IMHO and without any budget restrictions:
Macro shooting = resolution
If under controlled light conditions and with tripod I'd go for the camera with the highest resolution
==> 5DS(r), with "r" depending on what you like better
If the camera should be more versatile, if light could be sometimes not so good, if handhold would work against highest possible resolution I'd go for an universalist
==> 5D4 (or 5D3 if price is too high)
If budget is something to consider, I'd go for the best APS-C sensor:
==> 80D
Personally, I prefer a crop sensor for macros, as it gives you greater working distance. If you are buying new, then the 80D. If you already have a 70D or 7DII, the difference between them and the 80D is not that significant.
What ARE you shooting? What mags? <1:1, 1:1 - 5:1, >5:1? Tripod or handheld? What is your desired final output (web posting, gallery prints (size?), thumbnails vs. spreads in books)? Single frame or stacking?
I shoot flowers and various invertebrates, including reproduction up to 4-5:1, almost exclusively on tripod (spiders once in a while handheld), lots of stacking. For book from a 2-3 inch wide to full spread. For this I like the 5DsR with Zeiss makroplanar 100 and MPE 65, mainly to be able to pull off the page spreads. For 2-3 inches it is complete overkill. That also requires decent processing power (6 core MacPro soup can).
Are you happy with the image/print quality? If not, what is missing? If you are happy, then it is not a question of camera, but of lenses. If you think it is too blurry, then add MPs, either a 5D4, or a 5Ds/R. But again, macro is primarily a question of lenses and reproduction size (still no indication there), not of camera. Some people consider 1:10 = macro (I don't), and you can use microscope lenses on bellows and stack 1000 frames. So, again: what do you shoot? Why are you not happy with your current set-up?