They're not in the same price category. But if you want to buy a handheld you should buy psvita imo. It depends on what genres you like though.
About that... buy what you want. I mean, look first to the games before looking to the hardware itself. What are you with a strong handheld when the games aren't fun in your eyes?
i'll say none, both 3DS and Vita dont really have any game worthy of a purchase yet and laptop are a waste of money (unless you are actively travel from place to place).