Headfirst Alta. Channel switcher, covers the landscape of British tones I like with lots of flexibility, dual masters, effects loop, NFB and Depth controls, MIDI for switching channels and voicing options, big iron EL34, smaller builder with integrity. Current production, not unobtainium, but checks all the boxes for me.
My current amps cover that ground pretty well. If the Alta had been around 6-7 years ago, it's probably what I'd be using instead of the others. Who knows, if I decide to flip some of the others, I could still get one.