You may have heard different answers because it really depends on the goals & circumstances of the startup. I have a few companies at the moment, and they each are set up differently.

Short answer. If you might eventually want outside investment or to go public or to have a lot of employees with stock options, you should be a corporation, though you can elect to be an S corp at first (as opposed to a C corp). If you never plan on doing any of this, you might want to be an LLC because it is easier to deal with. If you are only going to be in one state, it is easiest to just create the legal entity there.