what are the best sounding Accuphase or Luxman amps/preamps?

The best sounding components are their top-of-the-line models. :-)

I was going to say the "most expensive ones" but  @yingtonggao said it first. I would think that these companies don't screw up the pricing.

Yet, the F40 was faster than the F50, so anything can happen....

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.

I prefer SS - class A.  I am considering the Accuphase A-48 amp which is rated at 45W at 8 ohms, 90 at 4 ohms, 180 at 2 ohms and 360W at 1 ohm.  It has a high damping factor of 800.  It is their smallest current production separate amp, but it is not small!

My speakers are efficient at 93dB and they have a minimum impedance of 3 ohms, so the A-48 should be a good match.

I would take C-2450 + A48 over any Luxman offerings. I own E-650 due to space restrictions, otherwise I would switch to Accuphase separates in a heartbeat.