The pocket edition is a sorely neglected piece of software and is very limited in what is can do.
360 is a great port that is picking up steam with the consistency of its updates and is slowly catching up with the PC. However, due to hardware limitations, word sizes are restricted to 1000x1000 blocks.
PC is the full game, is update first (and very, very frequently), is completely mod-able, and can even be played on the website in browser without needing to download the game.
So... yeah. PC