Late to the thread but this is a great discussion. I went through the same thing with a fairly tall board. I bought one of those squishy gel wrist rests first, and honestly it made things worse because I was just mashing my wrists down into it while typing. Switching to a firmer, lower rest that my palms only touched during pauses helped a lot, which lines up with what brisk said about it being a palm rest rather than a wrist rest. Also seconding the height point: dropping to a lower profile board did more for my comfort than any rest ever did.

Physiotherapists tend to recommend against wrist rests. When you are typing your hands should hover, when you aren’t then your hands should ideally move away from the keyboard altogether.

If you still use one anyway, rigid ones are less likely to compress veins/nerves in your wrist/hand and are more comfortable than they sound. Make sure you only rest your palm on it (and only when not typing), it’s not actually a “wrist” rest (also you’ll find better options searching for “palm rest” IME).

I am not a physio, this is all parroted from two physios I’ve talked to about wrist pain.