I don't use a thimble for piecing. For quilting, I use a basic Hemline metal thimble, the cheap ones you can find everywhere, and I use an Aunt Becky on my underfinger. The Hemline ones come in a few sizes, and since there are sizes smaller than the ones I wear (and I'm 4'11), it's probably a pretty wide range.
One thing that puzzles me is when people talk about using the top of the thimble for quilting. Surely you're meant to use the side, not the top? It sounds really uncomfortable. I'm looking at that silicone thimble and thinking, "But how are you meant to use it when the working part is silicone rather than metal?"
I tried an open-sided metal thimble made by Clover, in the hope that it would be less sweaty, but it was horribly uncomfortable. I've not tried leather since I'm vegan.