House of Edgar is one of my main suppliers for cloth for my kilts (Lochcarron being the other). I like them for several reasons:
1. They have a very nice range of tartans -- their "Old & Rare" range includes a lot of hard to find tartans that you would have to get special woven otherwise. And of course all the Irish county tartans can only be produced by them.
2. They have nice colors. Their "muted" color scheme, especially, is a nice alternative. It's darker than the ancient colors, but lighter than the modern. It's closer to actual traditional tartan colors than most of what you find available today.

I've always found their shipping to be quick and reliable.

I only wish that they did more tartans in heavy weight -- their entire Old & Rare range is medium weight, which I understand is more popular for standard kilts, but I really do prefer the heavy weight for four-yard kilts.

Aye,
Matt