Z2M. I had a ZHA setup and I'll give it to them, it was super easy to setup (barely an inconvenience). Then I bought a set of sockets with power monitoring but found that they used a non-standard way of reporting those stats.

They were seemingly quite new and both ZHA and Z2M had 'quirks' submitted very quickly to make them work, but while the Z2M quirk was approved and added almost straight away, 2 or 3 months later I was still waiting for the ZHA one to be approved.

Then, like you, I wanted to change the Zigbee channel and took the opportunity to switch to Z2M where the sockets and their power monitoring have been working perfectly ever since. It's definitely more complicated to setup initially but you get more control overall and, at least from my experience, the overall device support is much better.

Note: I did initially have loads of stability issues when making the switch, but it was due to me flashing the combined Zigbee+Thread firmware to my Sonoff stick. The fix was to turn off the OpenThread Border Router in the Silabs addon and then everything was stable again. I don't have any Thread devices yet, of course.