Best solution depends on best for who.
If the extra cost is not an issue best would be a GFCI breaker.
Best for the one buying the materials and getting paid a fixed amount regardless where the GFCI is would be to have a GFCI receptacle.
But then you may have to answer the inspector, is it receptacle accessible.
Lower end tubs may have a removable fiberglass / plastic side panel.
The norm is wrap it in tile.
If the tub motor side is adjacent to another room an access can be put in there.
Or in the ceiling below a panel with a hole in the floor to access. That would need some fire rating considerations.
It's to the owners benefit to have an access for service.
Seen in hotels panels made on the side of the tub that were tiled, and the panel caucked in (no grout around the panel).
Even then it needed a tile guy to remove the cover and many times repair the area.
The faceless is a compromise. You do have a bit more material and labor. The owner may or may not care about the extra wall box.
For servicing the GFCI breaker wins. At some point GFCI receptacles trip, fail, and used to need to be tested (UL 943 auto test I don't know much about).
Don't know how many times having to lay on the floor, blindly reaching in with an arm an a stubby to change out a bad GFCI receptacle hidden away somewhere. Come to find out he same person didn't bond the box or motor properly.
