For a bathroom window (higher humidity), which would you recommend: static cling or adhesive?

Both adhesive and static cling films can be installed in humid and moist conditions. If being installed on a shower door, mounting on the outside of the shower door is recommended. The benefit to using a static cling material is that it can be applied as many times as needed and can be reused if ever taken down. The adhesive material has limited application time and cannot be removed if ever taken down. As far as durability in a bathroom, both will work wonderfully.