If you want to start playing an instrument, you have to ask yourself, “How long will I have to practise?”, or ,” How long will it take?” You also have to consider the long hours ahead of you trying and trying again to learn that instrument.
If you desire to learn about harmony, intervals and the way music works, I would recommend the piano or the keyboard, because they are easy to visualize notes on.
If you love to make loud noises and create a racket, try your hand at a brass instrument such as the trumpet or the horn.
If you like delicate sounding pieces and sweet melodies, try a woodwind instrument such as the flute or the clarinet.
If you enjoy emotional or powerful music, try a string instrument such as the violin or the cello.
If you like heavy rock or metal, try the drums, the electric guitar or the bass guitar.
If you enjoy jazz music, try the saxophone or the trombone.
All in all, it is up to you which instrument, if any, you decide to play.