Kiwi Design Comfort Head Strap Compatible with Meta Quest 3
BOBOVR M3 mini Head Strap Accessories,Compatible with Quest 3,Elite Strap for Enhanced Support and Lightweight Design
What is the best strap to get for a 13 yrs old and someone over 50
Not fused about battery ones
Most will be better than the stock strap (depending on use case). Eg. the stock is good when resting your head against a headrest as it has minimal protrusion.
With most of these headsets, it's very much personal preference and, for example, where one prefers the weight of the unit to be positioned. Some straps hold the weight on top of the forehead (my preference) where others distribute the weight elsewhere.