I use a Kinesis advantage keyboard. It's expensive and ugly but comfortable. I would not go back to another keyboard ever again. Have a look at this review https://www.anandtech.com/show/7125/kinesis-advantage-review...
Tried to use it for 3 months, couldn’t adapt, had to sell it. Also, it has Cherry MX brown switches, which are not my favorite to say the least, with their middle-of-the-ground sort-of bumpiness. I much prefer either fully clicky or fully linear ones.
I used to have awful RSI and switching to the Kinesis Advantage for a year fixed it. I don't use it anymore but I don't use the apple keyboard either which I think caused the RSI in the first place, or maybe it was just how I was banging away on it.