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
alun
I tried RCA Clear Tops, EH, and Radiotechnique(cryoed) before settling on Mullards as the ones that sounded best to me...in 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?

Alun
I think they use 12AU7s? If so I would try RFT (E. German brand) and RadioTechnique (sold at Upscale Audio, I think).