Why do Tube Amps sound more romantic v SS amps


Question newbie on tube amps, why are tube amps according to people who own them say the sound is more say romantic sound vs SS amp ? 

What is better to own cost wise sound advantage single ended and push pull ?

Thanks guys excuse my inexperience on the tube issue.

128x128aseaman007

Harmonic distortion. "Golden age" studio outboard has made a major comeback in the post digital era as engineers try to put back what they lost from analogue tape in terms of distortion..

Its way more complex than that but, and forgive the generalisation, but tube amps with lots of even harmonic distortion tend to sound "romantic".