I think that me and five other people on this planet have no particular taste in music.I listen to any song I like, the lyrics or the track.The funny thing is that I can be very happy for some reason, and while I listen to the playlist my mood changes because of the song I listen to and keeps changing with every song, one of my friends even told me that I have schizophrenia😂 I would like to say that every person is free to listen to what he likes without others being intolerant of his opinion or his musical taste.

I think 'most horrible' is grammatically correct and 'horriblest' , although strictly speaking is grammatically incorrect, is used colloquially. Usually you can add 'est' to an adjective in English to make the superlative eg. big, biggest, small, smallest, but horrible is an exception to the rule. So it depends on how you would like to use the word and the context, maybe in formal writing you would use 'most horrible' but if chatting with friends you could use 'horriblest'.