Most Expensive, Nonsense,
Are you only considering Solid State, or Tube Models?
Tubes, the better question is, what tubes sound great 'to you' because it's not better, rather 'preferred'.
My Luxman 10 wpc tube amp is terrific for efficient speakers in a small space. It would be nearly criminal to put a more powerful/more expensive/most expensive amp in here.
The object was to be able to use tubes in my office, low power to minimize heat, size, increase placement options, and lower cost compared to more powerful category. Achieved!
here it is now
Never heard an Accuphase except in a showroom.