Technically, you didn't specify where: Lifeline, Shattered Skies, Stonehenge Offensive, Emancipation, Siege of Farbanti, Megalith or Trial Mission 5.
Or you meant in general.
Lifeline: No combat, therefore the 'best' plane is arguably the one that gets away from them the fastest and back to the return line. I believe the fastest accelerating plane in 4 is the Mir-2000.
Anywhere else in the canon campaign, but Farbanti, especially(which is what I'm guessing the original intent of the poll was): Speed is almost as important as raw turning, as you'll want to get the heck out of dodge whenever you find yourself with two or three of them taking "active interest" in you. Divide and conquer is the name of the game, IMO. Find or lure one away from the pack, and take him out before the others catch up. Everyone knows QAAMs are a crapshoot, though they can keep that particular Yellow preoccupied, and will buy you some peace for 30 seconds or so.
It's between the Su-37 and the S-37A, I think(though the ACTIVE and -22 are no slouches either). Su-37 gives it's X-02-beating turn rate, S-37A is a little faster off the line than the rest of the top tier(for getting away from angry Yellow double/triple-teams), with slightly lower turning.
I'd go with the S-37A, but SoF is a pretty decent place to use the Su-37's LASMs in the first phase(their top-attack flight programming helps them get around building obstuctions, and ground targets are fairly spread out anyway). In Emancipation, you don't have to worry about the Yellows double-teaming you, except possibly at San Profeta Airport(IIRC).
In Trial Mission 5: XMAA or XLAA plane, full stop(minus the X-02, the F-15ACTIVE is probably the winner). Fastest time comes from immediately stabbing them in the back with XMAAs and finishing off the last one with standards.
Edited by Timerlane, 10 April 2009 - 10:52 AM.