I myself would either go with charcoal grey hose, or some colour that goes well with the tartan.

There's a phenomenon with colours perhaps to be aware of, and that's when you put a certain colour with a certain tartan and it negates or sucks away that colour from the tartan rather than reinforcing it.

Our pipe band has lovely Muted Drummond of Perth kilts (seen in my avatar).

For several years, throughout the 90's, it was very popular amongst pipe bands to take all colour out of the uniform save for the kilt itself: pure white hose, black flashes, white shirts, black neckties, black jackets, black Glengarries. This resulted in a very crisp, clean look that made the tartan stand out and speak for itself.

Well around a year ago the band went with mid-grey hose and shirts, and the result was a dramatic muting/dulling of the tartan.

Likewise a tartan can have a lovely green that has interesting interactions with other colours in the tartan, but when paired with Lovat Green hose the green is sucked out of the tartan and the kilt becomes dull.

So many pipe bands, tired of the pure white hose look but aware of the dangers of coloured hose, are going to black hose. (I appreciate the motives but I personally don't care for black hose.)

This effect of coloured hose dulling the tartan of the kilt seems often to be avoided if the hose colour is as strong (saturated) as the colour in the kilt itself. The effect is seen to its worst if the hose colour is a duller, less saturated version of one of the colours in the kilt.

Offwhite hose should be avoided by people not wanting their Highland dress to look like it came from the 1980's: for better or worse fashion marches on. Great for 80's parties, though.

Charcoal hose are nice because they're dark enough to not interfere with the tartan, but not actually black, which interferes with the shoes.

By the way, I've never seen anyone mix charcoal grey jackets and hose with brown shoes and sporrans... I wonder if that works.