both of those car are stereotypical wannabe-rich cars around here.
you buy a BMW because all the neighbors drive one or a Merc, so if you showed up in a ford taurus, you wouldn't fit in.
the porsche is the middleage crisis car. every driver of one i have seen around here has graying hair, an expanding waitline, and looks like they just got done doing your taxes (which i'm sure they just did).
of course this is just around here, since i drive through malibu, santa monica, and westalke village (the richer parts of this area) these cars are awfully common.
whenever i go to my bank, there's always either a 360 or a gallardo, a maserati, an assortment of M3's and M5's, and the lot of porsches. kind of fun to park there though. but i'm sure you see what i mean.
test drive both and see which you like. if you are buying the car only for the bling or image aspect of it, you might want to reconsider. if you want fun and performance, then try each out.