Re: Holy Grail of Basses?
Any Pre-CBS Fender. For me- Pre-66 Jazz Basses, before the blocks, before the binding. I suppose the 60-62 with the Slab Boards and/or concentric knobs. The maple finger board Precisions from 57-60 are probably the priciest.
Checkerboard Binding Rics are always in command.
Plenty of boutique builders have built severely incredible basses, but way too fancy pants for my taste.
For more modern "vintagey" stuff, the Sadowsky basses seem to be held in pretty high regard.
Some day I'll get Scott Lentz to build me a bass...
The Gibson basses aren't as well regarded as they don't really have a lot of "name" players and the basses themselves don't have that "Fender Bass" sound.