Ian, you've used the Yamaha is so long that of course it is easy and intuitive for you.
However there is a rather steep learning curve. New users are always stumped by both the basics of the Registration system and of its many parameters. For example you can spend an hour setting up a registration and then lose it because you didn't save it twice. First the reg and then the bank as well. Then there are freeze settings in two separate locations. Then there are two, or three on some models, places to edit and save vocal parameters, etc.
My point is, all the systems are easy after you use them for a few years. To me, the easiest to learn and get around is Roland.
Korg is probably the toughest, but ultimately the most complete. The earlier Ketrons were nearly impossible. Technics was great.
Just random thoughts and rambles!