Perhaps some concrete ones, the green metal ones, I like, but the ones with bricks showing through, military lower 2 and military mid blocked, what I would do is have lots of blasted concrete, lots of smashed up and damaged, along with normal concrete, the reason I say this is that having lots of say the military mid blocked would look odd because its the same tex repeating, so for damage you have to do lots of variations so one doesn't get too much tiling standing out as it doesn't look natural, so for the damaged stuff Id do a load of different ones for concrete, plus you can bulk a pack out because you do plain ones, then damage them, gives at least double the textures for that section without double the work, so its handy that way.
You could even do damaged ones not just for concrete but for all of them, make the damage as an overlay, ie separate layer in photoshop or whatever you use, and then just add the overlay to all the textures, that can really bulk them out a lot, if you had 10 different damage layers, added to each texture, well its just increased the pack by 10 fold in size, and all one has to do is the 10 overlays, so for the time it takes for say 10 damage images to be made, you can use them to make the pack 10 times bigger, cost effective in both time plus giving more value to the product and therefore more value = more price value, it wins on all levels.
