While I own 2 Waterfords and they're great bikes I'm not sure they're going to be an investment. OTH, you forgot to mention the only custom bike that's already an instant investment and classic, Richard Sachs. He should have been #1 on the list.
He also forgot Spectrum.
I'm very biased, but I obviously agree with you...Sachs are going to be the bikes made now with the highest value in 30 years.