I really had only two things I was looking for in a pouch for my GNex:
1) I have an Incipio NGP case, so it had to be big enough to accomodate that.
2) A carabiner (or something like that) to attach it to my beltloop, bag, etc.
After much searching, I ended up with the Krusell Luna 4XL pouch. I got it today and it works very nicely. The outer leather is soft and the inside is suede. The phone (and case) fit snugly, but it's not a fight to get it out. The grip of the NGP case helps keep it firmly inside. The phone goes all the way in with about 1/2" to spare at the top. I substituted my own carabiner for the included round one. Krusell also makes a 3XL version which looks like it would fit an uncased GNex perfectly.