"tube" means nothing. it's basically an extremely outdated electronic part. "tube = warm and crispy sound" is marketing, not reality.
only really extremely elaborate and costly circuits can make tubes sound really good. buy cheap tube gear and you'll get crap. don't touch tube gear under 2000$, it will always be inferior to solid state.
now, talking about cheap "tube compressors" is even worse. that's marketing at it's best. a real tube compressor (and these are the really special sounding processors) are based on the vari-mu technique (which means the tube itself controls the compression) and start at > 4000$. everything else is a common solid state compressor with a simple and technically bad constructed tube gain stage - to make it distort the signal.
no, here's one thing that might shock you.. ..the reason why high end studio hardware companies use these costly tube circuits is BECAUSE OF THEIR EXTREME LINEARITY (low distortion) compared to solid state circuits. high end tube gear sounds pretty clean and "fast".
really "warm" sounding gear is actually solid state. the best example is all the Neve stuff, or Joe Meek.
but it's too easy to fool people with tubes "warmth". they look warm.
avoid cheap hardware compressors, they are really not worth it. invest that money in a better hardware mixing desk or save money for a really good compressor like the small and excellent neve portico compressor (or the tape emulator).