Hi,
I prefer valve in a Hi-Fi amp, there seems to be more musicality to them. The production of sound also to my mind appears smoother.
With regard to amps, valves NEVER went out of fashion. Nowadays folk are reproducing specific valve amps of old which have characterisic sounds. From my point of view there is absolutely no comparison between guitar valve and SS amps.
It is my experience that valves also have a larger dynamic range, this allows for passages of music or notes played to have greater attack and sustain. This makes the sound more "alive" in my opinion. Also, I believe that valves clip in a much less offensive manner, in Hi-Fi you would not want to drive them to clipping but certainly with guitar amps you may want to.
I suppose it also depends on what music you like. I played guitar for years, a VOX AC30 tube amp at max volume, through a distortion pedal, analogue delay, compressor and finally reverb. When recorded the music is again submitted to various effects especially compression to reduce dynamic range. Why on earth would I want to listen to this at 0.001% TDH?
If I had a good recording of the 1812 Overture ..... ah that a different thing.
At the end of the day it is what your ear appreciates, the cheaper one can achieve that the better.
Cheers
Andrew