M6 Mark II or 90D.Why is so hard to understand that some people want a decent quality 4K in a camera costing less than $2500 (R6). Not 1.7x crop with hunting contrast detect AF.
That would have been a decent update to the M50. The M6 has no crop but has the worst quality 4K of any APS-C camera on the market and it's quite expensive.
Although I would not consider either one of those as an M50 replacement.