Burton makes great boards. There is no real reason to stay away from them. People just say that because it's "cool" to bash the Nike of the snowboard world.
As for size, it depends on the manufacture. Look at their suggested weight ranges for a given deck, and that will give you guidelines. They vary from company to company. Thus while Brand X may say your in the 150-155 range, Brand Y may say 155-160.
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