after playing fingerstyle and acoustic guitar for decades, with a little noodling on the piano, a friend's band pressured me to play bass with them one night. three hours later, i realized for me playing the bass felt very right, unlike the guitar - i was in heaven doing it, even poorly, and offered to buy their bass on the spot (they said no). years later, due to an injury i was unable to play guitar or bass for a while, so took up with electronic drums, but ended up with a kala ubass, which was small enough to play even with shoulder problems. problem solved. i've toyed with the harp, keyboards, and still play guitar occasionally, but bass is the one for me. it's the one i learn on, practice on and spend time (and money) on.
i do sing, too, but these days if i had to choose singing or bass, it'd be bass all the way.