I believe the first commercially available non-tartan kilts were made by Howie Nicholsby of 21st Century kilts. Theirs tended to be dressier and more expensive, although they are the first to market a camouflage kilt. I'm reasonably certain that the first utilitarian kilt, that is, a kilt designed primarly as an affordable garment for daily wear, was the Utilikilt. It's certainly the most well-known.