2005 GTO or 2016 Z

Silverstone

If its stock, you're sitting somewhere around 350rwhp.

Rough comparison...

370Z - 300rwhp, 3300 lbs
GTO - 350rwhp, 3700lbs

The GTO is much easier to get power out of, obviously. People are reaching 400rwhp+ with cams and bolt-ons. Remember you're comparing two very different vehicles. I've never been a fan of most GM vehicles since they've always felt like they were designed for fatter people, flat/wide seats and whatnot, and felt a bit dull in handling. I do like the C7 Corvette, but that's, again, in a completely different classification. The 370Z can be looked at as a handling car while the GTO can be viewed as a tourer. Both are good cars, just have different purposes. If you want a V8, check out the new Mustang or Camaro. Those are pretty sweet from what I've seen.