Well, as far as superstrats go, I have a Yamaha RGX Standard, Ibanez RG570CT, Ibanez S7320 and Gibson M3.
Ibanez gets points for the nicest tremolo's, in my opinion.
I generally don't like the RG series, but mine has an alder body, giving it a more 'singing' tone with more sustain, which is quite impressive for a bolt-on.
The S7320 sounds huge because it's a 7-string, another thing that Ibanez is good at (although it's starting to get more common with other brands now).
The M3 is my overall favourite, because it's a vicious beast. The pickups are incredibly powerful, and it is the only set-neck of the bunch, and the only guitar that doesn't die out on the upper frets. It sings and sustains right up to the 24th fret, like a Les Paul would.
The Yamaha has the coolest looks, and is a nice overall player, but doesn't really excel in anything.
I've also tried some Jacksons over the years, and found that they play very well, but generally they sounded too dark, too 'metal' to me. They didn't have good classic rock or clean sounds.
So for me the best superstrat is a Gibson, as ironic as that may sound