For my view point the most important criteria for a sporran would be:

1. Does your hand fit easily into the pouch?

2. Is it large enough to carry your stuff? (Hopefully you don't have too much stuff to carry)

3. Does it open and close easily and fasten securely?

4. Is it reasonably soft?

I think if you can achieve this mix in a reasonable size, you would have a winner!

Jim