I seem to have got them back to front. Best rate is shallower/flatter, best angle is steeper.
Except when they both become the same!
If that pilot has recognized a need to outclimb rising terrain, best angle is likely most appropriate.
Not likely, ALWAYS, thats what it is there for and when you really need it you will appreciate that a foot the wrong way is the difference between flying over the mountain or being carried down it.