Tubes are not better. As a technician/engineer that started my career in the days of mil-spec tubes that you can no longer purchase, I can tell you no Class A tube amp can match solid state for linearity. They all produce non-linear amplification to one degree or another. However, some people prefer their sound to have the coloration produced by a non-linear amplifier because the non linear output sounds warmer.
@barjohn There is far more to it than just this. What is being ignored here is the simple fact that two decades into the 21st Century this is still a conversation. In any field, when a superior art appears (such as solid state), the prior art vanishes. As an example, no car manufacturer makes a flathead side valve engine anymore- overhead valves offer greater reliability and performance. But for some reason, even though tubes were declared 'obsolete' in the 1960s, they have persisted for over 60 years. That's longer than when they were the only game in town.
Its not just that 'people like the distortion of tubes'. There is far more to it than that. What is keeping tubes around is that people don't like the distortion of solid state (which manifests as harshness and brightness).
I've explained all of this, plus a solid state solution (because this really is all just engineering; there's no 'magic'), earlier in this thread.