I'll add my perspective from someone that is newish to leather work. I do leather work as a Hobby and I was in the same position as the OP when I wanted to upgrade my Tandy yellow poly mallet. After quite a bit of research I settled on a tapered maul weighing ~14 oz. The reason I went with a tapered maul is because I tend to rest my elbow on the table/desk when tooling. The angle on the maul head allows for a solid hit while I do that. It may seem like a small thing but, for me, it helped quite a bit. Before getting the tapered maul some of my strikes would slide off, especially when tilting a tool such as when tapering off a beveling run.
For me 14 oz is just right for tooling. It lets me tool for a couple of hours at a time effectively, but without too much stress/fatigue on my arm.
If you have the ability to try try different types/weights that would be ideal. If you don't have that ability, a 16 oz maul would be a good place to start.
Hope this helps.