Honestly, I feel that it depends on the environment and general mood of the artist or audience as well as the type of music being played.
I play guitar, it's a lot of fun to just jam out and it's a lot more portable lol, although I'm not too good
Piano As a studied musician, I will admit I first learned the guitar. But to study music, I found the piano easier to learn - and easier to convert knowledge of notation from keystroke to guitar/bass. I suck at drums.