Like I said before, the MP4 is technically the superior car, the 458 is the more exciting one. However, I've learned that McLaren is by far the better company to work with. Also, there's the increased horsepower with the MP4 (617 bhp), better fuel economy, comfort, and superior reliability. People that have driven both say the McLaren is also much easier to live with. When you dial it down it behaves like a normal coupe.
If for some reason I want a little more excitement, I'll just turn off the traction control.