Do I need a stand mixer to make good pizza dough? If so what should I get?
You don't need a stand mixer, but it's a shortcut for those of us who don't like kneading the dough.  You could also use a bread machine (most have an option to mix and kneed, but not bake), or a food processor (use a dough blade), or just knead by hand.

If you look, you can find some no-knead, or at least less-knead pizza dough recipes, and there's some styles of pizza crust that are more biscuit like than what most people think of as pizza.  (It's popular in Maryland, and it has the advantage that you don't have to wait or things to rise, etc, so there's no advance planning necessary other than pre-heating an oven).

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As for brands of mixer ... I won't get into that discussion, as I haven't owned enough of them to be able to give a good comparison.  Just make sure it has a warranty or a return policy, as my neighbor had some problems with the first model she bought ... she ended up going with a different brand because of all of the problems.