Locals are better because when using them in functions you can create reusable code. Code that is independent of the rest of your code so if you write a function once you never have to write it again, and you can use it in different games. Also I have found locals better because you can use the same variable name over and over for different things in the same game.Try that with globals and your variables will get scrambled. Another thing is that using local makes it easier to reload your game from a start screen.