Not OP, but I use the kinesis advantage but if I was going to pick one again I'd go with the ergodox, also had a keyboardio but switching between types is kinda tricky and annoying
Anecdotal, but ergodox flared up my RSI terribly. I think it might be the shear size of it and overstretching my pinkies with the shift keys pulling double duty with parenthesis.
I’m now a happy user of the kinesis advantage (though the configuration software pales in comparison to the ergodox) and feel so much better.
There's a number of options for replacing the control board on the kinesis advantage (or advantage2) with one that runs QMK, providing the same sort of configurability as the ergodox, and the advantage 360 pro runs on ZMK.
I've been on advantages for 20+ years at this point and haven't had any of the RSI that prompted the switch since.
Currently daily on a 360pro. Might want to sell it or reswitch it for something a little lighter and maybe even something linear. Maybe a silent red or lf red.
I bought and returned a Kinesis Advantage360 for a Realforce R3. The R3 isn't better, but if you don't possess the requisite mechanics for their ergonomics, there's no point in buying a Kinesis.
My guess is that, for most people, myself included, once one has invested the time in learning any particular ergonomic keyboard (Ultimate Hacking Keyboard, Ergodox, whatever), the switching costs are annoying that one just keeps using it
A small number of people seem to get obsessed with the narcissism of small differences in terms of switches, or minute aspects of positioning, or similar matters, but I find that one hits diminishing returns quickly and it's less the keyboard than what's done with it.