Of the two, I'd take the Fox body Mustang. It looks better (more agressive, less exotic) in my opinion. But, my ideal weekend warrior car is a 1999 Camaro Z28 with the following:
ZZ572 Crate engine
Dual-stage 300hp Nitrous kit
Tremec T-56
Ford 9" rear (or possibly GM 12-bolt...)
Gutted interior
Full roll cage
Recaro racing seats w/ 5-point harnesses
Massive drag radials
Badass rear suspension (haven't figured all the details out on that yet)
I think that'd be a nice compliment to my Regal (which will hopefully run low 13's and still have awesome ride comfort when I'm done modifying it) and my S12 (which would probably be driven more than the Camaro.. mmmm drift).
So who wants to give me the $25,000 to build that big block beast?