I used to learn classic acoustic guitar, then I stopped playing due to a lack of interest.
A few years later I started playing again when I got into metal music so I learnt a bunch of metal songs.
A few years later again I lost interest in learning new songs and I've since been altering the songs I did know into acoustic songs. Heaven Shall Burn sounds amazing on an acoustic guitar.
I also taught myself a few songs on the piano, but I don't own one so I can't play well or often.