If you want to upgrade the regular T12 gimbals, then go for the Hall effect gimbals (like this https://www.banggood.com/Jumper-V2-Hall-Gimbal-for-T8SG-V2-or-T8SG-V2-Plus-or-T12-or-T12-Plus-Radio-Transmitter-p-1370924.html or this https://s.click.aliexpress.com/e/_At9DZN).
Jumper T12 Pro already has Hall gimbals no need to upgrade them.

what kind of gimbals would you prefer, for upgrading a t12 pro?

thx