So, what ties do you like to wear with a TARTAN kilt?

Plain/solid?
The ties I wear most often.
One kilt (Georgia) has a prominent MacIntosh Red stripe; I've a wool tie (and flashes) to match.
Most of my kilts are predominantly green, I've a green tie that's a bit more subdued than the MacIntosh Red.
For funerals, I wear a black tie.

Tartan?
No. Not with a kilt, anyway. With a sportcoat, almost exclusively.

Stripes?
I've a regimental Legion tie, which I suppose I'd wear if need be with an Argyll jacket, but as our color guard wears white tropical uniform shirts with Legion dickies, the issue has never come up. I've a college tie in the stripe of my alma mater, but have never had the occasion to wear it with a kilt.

Cutesy?
My wife gave me a Guinness tie, which I was compelled to wear to our local Celtic Festival a few years back.