Tube suggestions for Unison Unico 80watt

Purchased a Unico a couple of weeks ago and am VERY impressed. I thought just for fun I would try out some different tubes to see the difference it makes. Can you give me suggestions as to what to look for in a quality tube. Thank you in advance
I tried RCA Clear Tops, EH, and Radiotechnique(cryoed) before settling on Mullards as the ones that sounded best to my system. It's really a matter of personal preference when changing tubes.
Mullards seem to be choice for many but there are a couple of different types. What type should I be looking for?

I think they use 12AU7s? If so I would try RFT (E. German brand) and RadioTechnique (sold at Upscale Audio, I think).
hello alun.
i've experienced with a few different tubes in my unico...
this is a must!take out those cheap jj 12au7's out of there
and replace with a good quality tube! the sonic improvement
will not be slight..ITS HUUUGE.

i tried new old stock military grade mullards cv-4003 and i
was not impressed with the sound,very sweet mids but lacked
overall control in the bass region and the highs were not
extended and rather veiled.

phillips miniwatts ecc82! very good tubes if you can get your hands on them,made in holland ,these solved the problems that the mullards had..tighter bass with very nice
top range extension.i think amperex bugle boys would sound
very similar to the minniwatts being produces in the same
plant i think!(?)
lastly telefunken ecc82 tubes,very epensive if you can find a good matched pair these are the deal! amazing trough the whole spectrum,find berlin production of these
from the 50's or 60's and that will be as good as an
12au7 tube gets.
find a good tube dealer that is reliable..i cannot stress
this point enough. since the amount of vintage tubes is slowly running low and hard to find,theyre have been recent
complaints of counterfit tubes on the market!
hope this helps and happy listening!