Is there any one piece of vintage gear you most wished you owned?

Kind of sort of.  A re-made Snell A/III perhaps.  Absolutely limitless bass and stereo image.

Would I buy one now?  No.  The woofers were made with extra mass and the mid and tweets are seriously outclassed today by better models... but if a modern remake appeared,  especially the curved upper baffle and huge bass cabinet I'd have to give them a listen. 

ADS L-1530

  Maybe, just maybe to own even one CD player that worked for more than 2 years, vintage or not!

I have a Phillips CD 880 that I bought new in the late 80's. It still works perfectly. It has never been serviced, and its gorgeous looking.

A pair of Western Electric 59A amps with meshplate 252 output tubes.  The tubes alone would be worth north of $60k, so the amps would probably be north of $150k.    I’ve heard a single amp, not a stereo pair, and it is easily the second best amp I’ve heard.  The best, a one-of OTL would be a good choice too, but it is a bit scary operationally, so I would be more comfortable with the 59A, not that this would ever be a reality.