I too love music and decided to teach myself to play the guitar.
I had the benefit of having played the violin since age 8 and got a degree in that plus piano, so I knew my way around music.
Why don't you try both?
The guitar will be easier - my approach was the draw out the six strings of the guitar on an A4 pad, just with a ruler and pen, then draw the fret lines on it - then look up the basic chords, C G D E A minor etc - draw them out on the guitar fretboard I had drawn - then work out how to play one chord (first finger goes there, second finger goes there) - then play from one chord to the other.
In the beginning I could not play music - twenty minutes of this per day and I could play three chords - going round and round those three chords - trying to make the shapes in time to the beat (down load a free metronome on your phone, set it to a slow beat and play the chords to the beat - NEVER sacrifice the beat for the notes / chord!! - but I digress - on my first day of playing the guitar, I drew out the diagrams for G, C, D, Aminor and E minor - and those are the chords for Pink Floyd Wish You Were Here.
To play the guitar you don't have to know much about music - why it works, what about it makes it work - you just play shapes - yo add a new shape every now and then and slowly your repertoire becomes bigger.
To play the piano, I would recommend you buy books and study them - My First Piano Book Sort of thing and try to understand theory. If you are that interested in music it would be good and it is not hard. Its simple.
But get started its the best hobby out there. I started over twenty years ago now and it has been the best thing ever. Plenty of times I have been frustrated by my playing and just found the next song to study and before long, inching along, I have made so much progress. I silence rooms now and have done some recording.
Good luck and I hope you really enjoy it.