If you don't like a super stiff wrist brace, these Cool Greys should be your go to. The Cool Grey are very supple and will feel more like a thick cloth on your wrist joint vs a stiff brace. You can tighten them how you want so you will have a ton of support, but they already feel broken in.
6" and less = Small
6.25" - 7" = Medium
7"-7.5" = Medium or Large depending on how much wrist coverage you want
7.5"+ = Large