Greens are the hardest colours to "mix and match" (ask your wife/girl friend). Bottle green is quite a strong colour and you would need to be sure of an exact match to your 2 green kilts, but lovat goes well with almost any green tartan and with dark tartans like the Black Watch and MacKenzie help to "lighten up" the overall appearance - I wore lovat hose with my Black Watch and they went very well together. Obviously won't go with your Royal Stewart, however. And if you get them you can ditch the white ones, which should only ever be worn by children and pipe bands. (As you may have gathered from this and other postings, I absolutely detest white hose!!!!)

However, if you're only going to get one pair of hose to wear with all 3 kilts I would suggest oatmeal (beige) might be best - goes with any tartan.