A good mat will have some padding but not so much that it becomes a bed. Normally 1/2-3/4" thick with a heavy cover that will be water resistant and easy to clean, the front will have a harder cover that won't flex so much and gives solid support to the rear bag. Options like flaps, pockets, peg holes can be nice but not really make a mat best in the world, rollup or fold up personal preference. Most of what has been listed will be a good choice, if you can get out to a range where people are using these mats andlook them over it would be the best way to make a decision.