Man, is that a loaded question. You'll get opinions out the wazoo. So here's a bit of mine as well :)
I have a '93 5.0 LX. When I first bought it, I loved it. Now, it's got a few years and a few miles on it, and it's starting to show it's age. But it still feels tight, and runs out really nicely, and every time I get a new set of tires on it, it's like I got a new car. Right now it could use a coat of paint, and some seat covers, and maybe some headlights that are a bit more transparent (deterioration of the lens, I think; plastic, what can ya do?). I still like the car, like the lines, like the push of the wheels out back. Fox-bodied Mustangs are are sort of plain, but almost infinitely moddable (if thats even a word).
I also own a '01 Bullitt. I currently love this car (it's still new to me). It has amenities that it shares with other GT's of the same year, such as air bags on both sides, and abs discs all the way around, but it also has quite a bit more horsepower in stock trim over the '93 in stock trim. Being a Bullitt, it also has a few amenities that add to it, such as subframe connectors, revalved Tokico shocks and struts, a slightly lower stance, a nice leather interior, fancy wheels, and a limited build, just to list a bit. It's a blast to drive. I suppose in a few years, it might be less fun, but that's then.
So if I were to have to choose between the two, it'd be the Bullitt. Or if I couldn't have it, then a '99 and up GT. The '93 is still fun, but dated, and the newer GT's are simply further up the evolutionary ladder. Brakes are probably one of the biggest downfalls of a stock Fox bodied Mustang, imo. Well, the handling isn't exactly crisp, either. If money isn't a problem, and you're looking for a good daily driver that you can have fun with, then get a newer model GT. It's not a big block, but it'll have you grinning.