Do you use one brand of electronics or are you mixing brands what has worked best for you?

Mix and match was required to get truly great sound when many of us started. Typically the founder only produced one exceptional product. However, these days some of the surviving companies along with some newer ones have produced top sounding and synergistic components. In these cases (when the house sound is aligned with your personal preferences) then purchasing all from the same vendor it preferable. 

For most of my fifty years in audio I have owned an Audio Research component... only in the last five years was I financially able to invest in the entire suite... and the synergy is amazing. You can see my systems under my UserID. 

I use for example an Edifier powered speakers...

It would be foolish to discard the Edifier sub designed for it  at a low cost price...

it is amazingly good system for the price... I will not upgrade it which was my intention after buying only the small speakers ...

 But generally it is better to look for any compatible component  from any company  if the S.Q. /price ratio is probable and the electrical synergy assured ...

There is no rule here except common sense ....

I mix and match.

I find that designers often appeal to me at one type of component but not all.

Example -- my music system:

Koetsu cartridge

Graham arm

VPI table

Manley phono preamp

Pass preamp and monoblocks

Thiel speakers

plus

McIntosh tuner

Sony SACD player

Nakamichi cassette deck

Rane equalizer

Audioquest cables

Mix n match for sure

Depends, I follow sonic choices not dogmatic mix or same brand.

For my SS main system, it’s currently the same.  I’ll eventually buy a second SS amp for variety like GanFET, sliding Class A, Class N…

For my flea watt system, it’s different as I’m investigating tube amps