First and foremost, tube amps offer a warm and natural tone that is difficult to replicate with a solid-state amp. Tube amps use vacuum tubes to amplify the signal from your guitar, which creates a smooth and rich sound that is highly desirable in many genres of music, from blues to rock to jazz. Solid-state amps, on the other hand, use transistors to amplify the signal, which can create a more sterile and artificial sound.
Another reason why guitarists choose tube amps is their dynamic response. Tube amps are known for their ability to respond to the player's touch and playing style, creating a more expressive and organic sound. This is because the vacuum tubes in a tube amp are sensitive to changes in voltage, which creates a more dynamic and responsive playing experience. In contrast, solid-state amps can sometimes feel "flat" and unresponsive, lacking the same level of nuance and expressiveness.
Tube amps also have a certain "magic" that many guitarists find appealing. They can add a certain amount of "grit" or "bite" to your sound, which can be great for achieving that classic rock tone or adding some extra punch to your solos. This is because the vacuum tubes in a tube amp naturally create some distortion when pushed to their limits, which can add a desirable level of harmonic complexity to your sound. Solid-state amps, on the other hand, can sound harsh and unpleasant when pushed too hard.
Finally, many guitarists simply prefer the aesthetics and feel of a tube amp. Tube amps are often housed in sturdy metal cases with large, glowing vacuum tubes that add to the "cool factor" of playing guitar. They also tend to be heavier and more substantial than solid-state amps, which can give them a more "premium" feel. While this may not be the most important factor in choosing an amp, it can certainly be a deciding factor for some players.
In conclusion, there are many reasons why guitarists choose tube amps over solid-state amps. From their warm and natural tone to their dynamic response and unique "magic," tube amps offer a level of nuance and expressiveness that many players find essential to their playing style. While solid-state amps have their own strengths and can be a great choice for certain genres and playing styles, for many guitarists, the allure of a tube amp is simply too strong to resist.