boy oh boy another one of these debates here.
same thing, tube vs solid state, digital vs analog, gibson vs fender, G&L or fender, Heritage or Gibson.... the list goes on. Guitarists are a gearwhoring bunch compared to other musicians (violinist, pianist, drummers, bassists). In any case here's my take.
I feel that this "tube preference" is attributed to history and influence. it all started from tube amplification, that is powerful. many people seek to find "traditional" tones and these translates to buying things that utilises tube technology. and a good bunch of us have guitar idols/influences who use tube amplification as well, in fact as far as i can remember, most great guitarists use tube amplification. its just one more step to attaining that "lush thick organic" whatever you might wana call it (sexy, orgasmic, raunchy, shimmering, pristine, lovely...) tone. In all honesty, it never totally works out. you might have his gear, you'd never have his mind, fingers, phrasing, vibe.
I have played plenty of tube amps, owned several and i have to say, they're nice. I am no audiophile claiming to be able to distinguish a SS amp from a tube amp. BUT i find that tube amps, when pushed (higher volume), they tend to sound better. so for you folks out there who have a 231312321 watt tube amp, but play at the lowest setting, you're really not getting much outta the amp. Most people prefer to use tube amps for this reason too, to push the amp to a state where it "responds" to your pick attack. I have tried this setting and you can NEVER achieve this nicely with a SS amp. The state where your cleans hang on the verge of being overdriven, place a lil' more attack, the notes are slightly overdriven.
BUT, i have sold my tube amps away. too much hassle for me. yes stone me tube purveyors but I have had so many problems, hissing, microphobic tubes, unmatched tubes, phase inverter tube.... yada yada... heat problems.... ventilation.... tube amps are very picky on their tubes from my experience. i'm back to SS, way more reliable for a gig, especially when i do not have the liberty to take backup amps, its lighter.
There is no better honestly, it depends what you prioritise.