I don't think is one particular "holy grail" of bikes. Too many fine builders at one time, and now, to say one is better then the other, although if I were to limit the holy grail to a field of bikes it would be almost any bike with chrome lugs and chrome half forks and half stays. I could list hundreds of bikes I like the looks of but it would take forever. Here's one modern example using stainless steel that looks really cool:
http://www.andersoncustombicycles.co...ery/index.html
This one is really cool, look closely and you'll see long point lugs just a fantastic look:
http://www.merciancycles.co.uk/galle...ery-image/180/
or this Gios:
http://www.giostorino.it/telai/gios-super-record-strada
Then this classic:
http://www.google.com/imgres?start=5...:429,r:0,s:542
I need to stop, lots and lots of nice "Holy Grail" bikes out there, just to many to nail down to just one.