I think Presbyterian would be the obvious winner in a denomination : kilt wearer ratio contests.

I wouldn't rule out Catholic as having many kiltees, but Catholic being so prolific, I don't think it would win if it were based on percentage.

I wear my kilt to the Nondenominational service. Since Nondenominational seems like it has become a denomination, I would say that it might be the highest non- Presbyterian kilt : people ratio.