I need help finding a quality replacement axle
Broken axles are an inherent feature of the 'freewheel' hub design. They happen because the load from wheel bearings is close to center, where it has more leverage than closer to axle ends. Newer 'freehub' cassette designs solve the problem with either having bearings inside the cassette close to axle end or with oversized axle.

The best option would be replacing the rear hub with a freehub type. The easiest way of doing this is replacing the entire rear wheel. If this is not an option, an original axle from known brand should be expected to last longer than random junk from Amazon or Aliexpress or at least have a warranty. A solid axle does not help, because the reason for breaking is tension from bending the axle. The tension is greatest at the surface of the axle, so solid interior does not help but the compression from quick release skewer slightly reduces it.