I didn't realize how many supercars there are now. Economy must be headed for an upswing(*).
For true supercar supercardom, I'd have to say the Zonda, as ugly as it is. I have a feeling nothing else listed can touch it. The Saleen has that wonderful American sound, but I'd prefer it on a Mustang or Corvette, not a supercar. Fast and crude, which is not a combination that makes a supercar. The Enzo may be great, but I don't think it can hold up to the Zonda...if only just. It's definitely an excellent exercise of function first, form one-hundred-and-second. The Lamborghini isn't up to the task, either, and less so than the Enzo. I like the looks, but it's more VAG than ITA.
That leaves the Porsche. Which is spectacular. But not up to the limits of the Zonda (surprise). However, it does seem to ooze supercar...supercar-whatever. Moreover, like the Zonda (and Saleen and Enzo), it has extreme character. Not just its own character, but an extreme version of the "company standard" character. The Enzo is an extreme 360M, the Saleen an extreme S351 (I think), and the Porsche is a modern & extreme 550 Spyder (or Boxster; your choice).
So my choice? The Porsche. It's not the fastest, or the most-anything, but it's got a great balance of everything (and quite accomplished in all aspects).
I don't believe in Murray's extremely limited view of what defines a supercar (just as Wheeler's definition of a sports car is foolishly narrow-minded in today's market).
(*)There was a theory put out by someone that supercars come to market at the low points in the economic flow, having been conceived during a boom, only to arrive way too late, right in time for the lowest point in a recession, with nothing but an upswing to follow.