A jeep? do you realize how much money you're going to putting into that thing on a weekly basis? seriously, you're only going to regret it in the long run - unless you're very well off.
mind you a mustang isn't going to be that much better.
Honestly, i HATE SUV's and most American cars. Really i only like the Ford Focus, and that's because i'm a fan of rally racing. The new focuses look like shit BTW.
Whatever you decide on, good luck.
Personally i'd recommend an older Toyota Supra if you want a car with some power. That thing would blow a mustang out of the water.