Out of all of those I've driven a LS1 Z28 A4 and M6 as well as a 350Z M6. The LS1 has a lot of torque to pin you back in the seat. But as a every-day driver I couldn't stand the seats or the headroom or the long 6spd throws. The 350Z, is a cool car, I really liked it and wanted to get one of these when I was shopping for the Mustang. I test drove a 04 Track model fully loaded. The sticker was $35k, a little more than I could afford, but I wanted to drive it. It has a smooth ride for a sports car, handles like a dream, and had quite a few luxury features to it, and is quick w/a nice stock exhaust note. Basically I picked the GT because the performance is about what a 350Z is, and I got it for $18k fully loaded as a demo. I would've rather had the 350Z, but they weren't willing to give me the credit for it and wasn't negotiable in price. Now I'm glad I have the GT, I really like it now over the 350Z. I didn't want the LS1's due to the fact they were used, cost $22 and 23k, and I didn't really liked the way they drove.