Best Vintage tube amp / preamp manufacturer

Dynaco was likely never considered "best" in sheer performance, but it could certainly be argued that they were best bang for the buck.  Very good gear for the money... they sold a boatload, and are still somewhat relevant today.

Eico, Scott, Stromberg Carlson all had a presence too.

Why are Western Electric so expensive?  Is it primarily collectibility or

sound?
 

With Western Electric, it is both sound and collector value that makes its gear so expensive.  The circuits tend to be simple and one can find clones made with modern parts.  Many such clones sound quite good, but, when one hears a vintage amp in good condition, or clones using expensive original parts, it is clear that the quality of the parts sets their gear apart.

What distinguishes Western Electrics is the terrific sounding midrange and very dynamic, yet natural sound.  The downside of the sound is a soft, somewhat restricted top end and a lack of extreme bottom end extension too.  

I worked on a lot when I was putting myself thru college working as a service technician.

The best preamp from that time for me has been the Citation 1 preamp from Harmon Kardon. I prefer it to both the Marantz 7 preamp and the Mac stuff. I don't know of a solid state preamp from that period that was really in the running; the best of those I worked on was the old Accuphase, which in my impression was built a lot better than it sounded, although it didn't sound bad. Of course this assumes that the equipment is properly refurbished.

The best power amp of that period also seems to be an HK- the Citation 2 although I never liked the power supply in that amp as it needs proper attention to detail when rebuilding it. If properly refurbished it easily kept up with ARC of the period, as well as anything from Mac or Marantz. None of the solid state amps of that era were on the same level, although some of them were quite interesting simply out of what they accomplished at the time. Semiconductors were not up to snuff in the 1960s and barely so in the early 1970s. Funny though, the colorations of early semiconductor effects pedals for guitar make them really popular and collectable nowadays.

I have an use a 1961 MC240 that was significantly modified by Mike Samra. IMO some of the best output transformers ever made.. IF you want to hear what your gear is capable of, modern power supply bridge / caps / regulation, pristine nos tubes, great coupling and interstage caps and importantly isolation… even the dense 50# MC240 greatly benefits, i use HRS.