Which used Ferrari 575M coupe should I buy?
The 575 was derived from the 550, but unlike that car, the 575 came only as a coupe for most of its life. Mind you, that's no bad thing. The 550 Barchetta soft-top was vastly more expensive, and Grand Tourers don't really work when they haven't got a roof.
The coupe body suits the car's character perfectly, and it's faster than the soft-top, which is heavier because of the extra weight of its roof-folding mechanism.