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

JBL 4350 monitors, first speaker I really fell hard for...couldn't even dream of owning them at the time ~1976.  They are monsters and one of the A'gonrs has two pair I believe.

Stax electrostatic loudspeakers

ESS AMT-1 Towers, A Marantz 7C and an original Ampzilla.  The AMT-1 Towers were a 10" woofer transmission line version of the original AMT-1, with much more linear bass and better driver integration than the ported 2-way, due IMO to its higher placement closer to ear level.  The 7C is a well known legend of HiFi, and the Ampzilla was the culmination of Jim Bongiorno's career...the first really harshness-free high powered amp.  I spent a lot of time enjoying all of these, but never owned them.

JBL Everest (Model DD55000) with matching JBL18’’ Everest subwoofers (Model 50000).

TDL Reference Monitors

Mission 767

Rogers studio 1

Cyrus 2 w/ outboard power supply