re: Poker & Which stakes to play?
There are probably some exceptions, but in most cases, it's better to full-stack at the lower level. The overall quality of the opponents rates to be at least a little lower, and you give yourself the maximum opportunity to profit from their poor plays and errors.
Plus short-stacking successfully involves making changes in your play style. At these levels, you're better served to stick with improving your game in the ways you need to rather than forcing yourself to make even more changes unnecessarily.