selecting a knife roll
I searched long and hard for the perfect roll but it doesn't exist... jb prince used to carry the "knife jack" but it has disapeared. You really need to find a place to buy one take it home and cram everything in and see how it works. I wound up with a 12 pocket but i double up on some pockets. JB prince has some nice ones. But they all work pretty well, best investment imo is some magnetic edge guards, durable and effective.
It depends on the types of knives you'll be carrying. Most knife rolls have different width pockets. You want to find one that has enough pockets for your larger knives. If you're using a cleaver or santoku, take those into account...therefore, a 12 pocket roll might not fit 12 knives, unless you don't mind doubling up. And if you use a long steel, make sure you get one that can accommodate that. I am always looking to slim down and not carry so much so I prefer a less bulky roll. The looks and style are mostly personal preference.