I am using NOS Mullards and Telefunkens only.
In order to get the tone you desire, you will need to hear each tube.
The NOS Mullards are very sweet sounding and warm. The Telefunkens add a bit of Fendery tone to the amp with a bit more upper end gliss, but the saturation on channel two is very good. Put a NOS Mullard 12AU7 in V-2 and a Telefunken 12AU7, or 12AT7 in V-1 as that V-tube will set the basic tone for the entire amp, depending on what you prefer.
There are other fine tubes that I sometimes use in the pre-amp section, such as NOS French tubes, NOS RFT's, NOS Brimars, NOS Phillips, or NOS Amperex Bugle Boys.
Also make sure you use a balanced 12AT7 (I believe that is the tube type used here) in the phase inverter. It makes a difference.
I have
a Celestion Vintage 30 speaker, which came with the amp, and I use a Weber Beam Blocker in front of it. It cuts the harshness right in front of the cone, and disperses the sound better.
I am using JJ KT77's for my power tubes.