The only criteria you listed for buying your next car was implied that you want to go fast in a straight line. Stock, an Neon SRT-4 will be quicker after first gear traction issues are gone and be cheaper to make a little quicker. It also costs $5k less than a base GT (assuming no employee discounts on either).
Mustang can be made quicker w/ a rear gear swap (cheap), or by forced induction(expensive). It's much easier (and fun) to control RWD power. You're in MI, so save $800-1000 for snow tires and wheels for either one.
That said, these two vehilces are so different in terms of driving feel, interior, ride, and looks. We can all list what WE like better ,but you won't have a clue until you drive them both.
I'd also not wanna buy the Neon SRT-4 w/ the Caliber SRT-4 coming soon for about the same price. I believe it will be far superiors a vehicle to live with every day.
