Since we're on the topic of comparo's, im going to do my own, being that i've owned both.
In the looks department, the Z wins easily, just the other day I was talking to a female friend of mine and told her that I bought a new Mustang and she made it a point to mention that she thought my Z was a "sexy" car, and while the Mustang has its own appeal, its a bit bland for her taste, and I'll concur, its pretty plain jane, it looks big and beefy like a muscle car should, and I like that.
The interior of the Z wins easily as well, I liked the fact that my Z fit me like a glove, the seats bolstered well, the push button start, the color scheme, the overall layout, I loved it. Only thing I hated was the stupid LED fuel gauge. While I dont hate the Mustang interior, its really plain, nothin fancy about it, I didnt buy the car for the interior
Handling, once again, the Z wins in my opinion, while the mag racers say that the Mustang hangs right along with it, I dont think it does, the stang feels heavy through the turns, it doesnt inspire confidence for me, it just doesnt feel nimble like my Z did. It'll probably handle alot better than I give it credit for, but i'm too nervous to find out. Can you add sway bars, coilovers and make it handle like an F1 car? sure you can, but the car will still be 300lbs heavier and have a higher center of gravity.
Power, the Z COMPLETELY loses in this department hands down, no if's, and's, or's, or buts. I had just about every bolt on mod the Z could get and a tune and it still had no torque to speak of, and it was the torque that I craved. When I get on it in my 5.0, it throws me back into my seat, the tires smoke effortlessly, i've even chirped it in 4th gear. The transmission is also much much more smooth than the Z, there is no notchyness to speak of, although there is that familiar "clank" when bangin through the gears at low rpms.
Technologically, the Mustang wins as well. While the SRM was a nice touch, I thought of it more as a gimmick than something that would add any kind of performance to the car. People have been throttle blipping since the beginning of the automobile. The Mustang has multiple modes of traction control that can be changed at the touch of a button, it even has a sport mode that stiffens the turning of the steering wheel and allows you to get on it without having to worry about your engine cutting power.
Overall, i'm happy with my purchase, I love it and i'm excited about driving it every day just like I was with my Z. You cant go wrong with either car fellas, these comparo articles really need to go, fun reads, but contribute nothing to alter decisions IMHO.