If I were going for a road bike I’d probably go with Rourke from your list, as I’m not up on road geometry, and I’d be confident in them. You would have to be fine with just TIG welding though as they don’t do brazing IIRC. If I knew exactly what I wanted then Kevin Sayles – either fillet brazed steel or lugged 953 would be my choice, again from your list of builders.
I have an Enigma mtb but it isn’t quite built up yet so can’t comment on it really. It isn’t strictly custom for me, although it is unique, as I bought the one-off fillet brazed ex-demo that STW reviewed.
My experience of custom (mtb) frames so far, is know what you want and make sure the builder agrees to make it to your specifications. Produce a drawing. The reason I bought the Enigma (a bit of a rebound purchase and it was half price – which helped of course) is that another builder/company made a right hash of my custom frame project and I didn’t accept it – wasn’t anything like my drawing and specs and had serious flaws. I won’t name any names but safe to say that the company hasn’t been mentioned up to now on this thread.
Mather was my original choice, but despite being on his ‘list’ and agreeing to make a start on the consultation stages by at least over a year ago, ignoring all my emails, I’ve decided he wouldn’t be the best choice – should anything go wrong or I needed a repair. Commuincation is key.
All the best