All those lenses get you 1:1 magnification at closest focus. The question is how close to your subjects you want to be (or can get to). The DA 35mm ltd macro is probably a most versatile choice, because it allows macro, street photography, architecture, landscape photography, etc., but ironically its probably the hardest to use for macro, because you have to get so close to your subject. If its not moving, thats not a problem, though. The 100mm is great because you don't have to be as near to your subject for 1:1 macro and it is a great lens for portraits, even for some wildlife shots and the like. The 50 is in between and allows a bit of each. Thing is, none of these lenses is a bad choice, they all perform really well. I suggest you just zoom your 18-135mm to 35mm, 50mm and 100mm and decide which focal length you find the most useful for your needs.
Oh, you can also look at FA or F series macro lenses. These are older lenses, but they have full automation and AF. Sometimes they can be found used and can cost a little less than new DFA lenses. Check out the lens review database on this forum and type in "
macro" - beware though that not all macro lenses have the same max. magnification. Some only go to 1:2, maybe not even that. Of course, you might not even need true 1:1 macro.