I seem to remember that, back in the 60s, Guild 12-strings were fairly common and were considered to be quite good.

I had the impression that the Guild company more-or-less specialized in 12-strings. Perhaps they made more of them (in comparison to their 6-string output) than Gibson or Martin, or maybe it's just that their 12s were more affordable than those sold by their competitors without being terribly inferior.

I'm no expert on vintage guitars, however (except for the one that I have owned for years and do not intend to sell.) I'm sure that better answers will be forthcoming from habitual buyers/sellers who know the market inside-out.