I owned a couple of Olivers back in the early 70s that I wish I'd hung on to.
One was a really cool oddball, a Powerflex 500 with two Altec 15"s. The head was mounted inside the top of the cab and motorized. It would rise up when turned on and sink back down when turned off. It also had a cool spacey looking plexiglass panel that lit up green when it was on. Great sounding 65W all-tube amp that I sold when I got my first SVT; I was playing primarily bass at the time and the SVT had loads more power.
Another was a 35W Oliver 1x15 combo amp, the B120. Originally designed with bass in mind but underpowered, it made a good guitar amp. I used it for cleans with a big band, then later sold it in favor of a MusicMan. The B120 had really good tone controls, almost like having a graphic: regular B-M-T plus ultra low and ultra high bands. For a while Berklee had these in all the practice rooms.
The other one I regret parting with was a Marshall, an early-JCM800 2x12 50W combo that sounded just phenomenal. Marshalls had become somewhat more consistent by the 80s IMO, but every once in awhile you'd still encounter one that was exceptionally alive and responsive and sweet sounding. I think that still holds true even today - some just have extra mojo compared to the rest. This was one of those amps, and I knew it. But when I closed my studio I had to lighten the load; no room in my tiny apartment and couldn't afford storage space. I'd pretty much bankrupted myself trying to keep the business going and needed money badly at the time.
So I sold the best Marshall I've ever owned - and a nice blackface Bassman too - along with a bunch of studio gear, and some other stuff that I don't miss much. I have several good blackface amps again by now, but in thirty years I haven't found another Marshall that compares to the JCM I let go. Wish I been able to keep it.