Welcome to the forum Clock King!
Personally I wouldn’t go any stronger than 5X for
use with average sized clocks. That should get you in close enough for most clock work. For closer inspection like pivot or pallet finishes I usually use a 7X to 10x watchmakers loupe.
I haven’t used one much so just coming from my limited experience.
Maybe someone else can add to this.
Hope it’s helpful,
Howard