I want to learn an instrument...(read details)...?

Everyone is different.

You just have to try them all out to get even an idea of what is ahead, and IF you have the interests or even curiosity to continue any further experience with any one of them.

And... this can ALL be accomplished and very possible well before you die, only if you accept what wil be ahead in learning and appreciating any instrument or voice and singing applications you may consider in the next few years, before you pass on.

You will soon discover what is really difficult, other than making up your mind. As well, should come to appreciate better of any instrument of choice when it comes to its sound. Or, come to that of the human, singing voice.

Its all out there to explore. Get to a music store, and check things out.

One can live better through the enjoyment of music, and better, when one can create it at will.

Piano is easier to just pick up and play, but harder to actually get good at. After you get calluses and get used to the finger positions for just like 3 chords on guitar, you can play like a million songs and it actually doesn't sound bad. However, neither instrument is really difficult; they both make excellent starting instruments. Learning piano also introduces you to sheet music, which is unnecessary with guitars, but crucial when playing most any other instrument. I think guitar sounds better until you start getting "fluent" with the piano. I started learning both instruments around the same time, but if you had to choose, I'd recommend guitar, just for price's sake. You can find really cheap ones for around $60 at music pawn shops and you dont need to buy a bunch of sheet music books in order to play it.

PS-If you want a guitar, a lot of people recommend starting with an electric, since the strings are closer to the neck and easier to push down, but electrics are heavier, they're not portable, you have to buy an amp, and you cant play them in the middle of the night, so, in my experience, not as fun to play...but if you enjoy the sound better, go for it! :)

Personally, I would favor the guitar (more transportable and enjoyable as a solo instrument) -- ANY musical instrument (or voice) requires hard work to be any where near efficient and/or accomplised with.