Mono Block tube amp or Stereo Tube amplifier?

Two monaural amps of a certain power are no different than a stereo amp of the same power for each channel. Basically you cut the chassis in half and duplicate the power supply, perhaps at a lower power level suitable for one channel.

The advantage of monoblock amps is that they can be located right next to the speakers, and for high power systems, you can pick them up without throwing your back out.

In a well designed stereo amp there is no crosstalk between channels (contrary to a common idea).

I have five monoblocks in my multichannel system.

The main advantage of a monoblock is that it does not share power supply and grounding circuits with the other channel. This can result in better bass, lower distortion (greater transparency), less crosstalk (more imaging information).

I run long interconnects and I have a balanced line system, so the interconnects are inexpensive (and 25 feet long). OTOH I keep my speaker cables as short as possible, as that allows a tube amp more definition and better bass delivery; something that is a lot harder with a stereo amp.

Monoblocks rarely draw more power, nor do they make more heat if they are the same power and class of operation as an equivalent stereo amp.

Mono block is the way to go. Check out the VAS line, warm sound, can drive almost all speakers and have great resale value as you move up to more powerful mons's.