I have heard "real" triodes (300B) and pentodes wired in triode (EL34) both sounding great and both sounding poor. It is very hard to generalize as many factors come into play such as negative feedback, circuit design, power supply, capacitors etc etc.
Notwithstanding the above, I have had more success with true single ended triode tube amplifiers paired with a correct speaker sounding the best.
Notwithstanding the above, I have had more success with true single ended triode tube amplifiers paired with a correct speaker sounding the best.