The only medicinal aloes I am aware of are Aloe vera/barbadensis and Aloe ferox. I have both and think they work about the same for external use. Aloe ferox gets much bigger and has pretty sharp thorns so not really houseplant material
Aloes are pretty good with poor conditions, mine only get watered a few times a year during the summer and are in partial shade and stay fat and green. Aloe vera throws off offsets like mad. The only thing they don't like out here is full summer sun. They shrivel and turn bronze and just look miserable.
Aloe vera works amazingly well for sunburn and also for different minor skin conditions I have found. Aloe ferox too!