What speaker has the best high frequencies?


I have a Spatial Audio X5 with a wide band horn loaded AMT (Air Motion Transformer) which handles high frequencies (1k and up?). It is big, about 6” x 1”. I feel it is much better than the 1” tweeter found in most speakers.  I honestly don’t know how this AMT is different from, say, ribbon tweeter.  This leads me to think, who or what speaker has the best high frequencies?  I heard good things about the B&W diamond tweeter, but it is still a 1” tweeter.  What else is out there?  I think size makes a difference.  In this case, is it a larger ribbing tweeter better than most 1” tweeters?  
gte357s
Maybe we can agree that a tweeter that goes in when it should go out is not great ?????
The ribbon tweeter (raal) specially made for ascend acoustics in their sierra towers has an amazing amount of clarity. 
I’ve tamed the Heils and they sound great with plenty of top end extension. I use them in a 2.5 way with JBL 2241H 18" and JBL 2251J 10". My own design crossovers.

I created acoustic lenses for them and insert a piece of foam to the rear to reduce reflections improving imaging. Here you see the RTA on the couch where I sit. There is no eq or digital processing of any kind being used here nor is the room acoustically treated in any way

Curve is actually a bit smoother at the top than shown due to additional crossover mods I’ve made since. Ignore the "floor/wall bounce depressions" at the low end.

Note this is ~+-5 dBA from ~32 Hz to beyond audibility (with a nice smooth curve) on the couch with no eq or room correction being used! And no woofer foams to ever replace.

http://www.audioheritage.org/photopost/data//500/medium/DSC_001011.JPG
http://www.audioheritage.org/photopost/data//500/medium/DSC_00171.JPG http://www.audioheritage.org/photopost/data//500/medium/DSC_00151.JPG
http://www.audioheritage.org/photopost/data//500/medium/DSC_00122.JPG

Take a listen:
https://youtu.be/JpjCAtrBjTI
https://youtu.be/qzjztUEy2V8


Amps/preamps with tone controls would have come in very useful right now. You could have just turned up the treble and voila. Simple.....
Well, since size of the tweeter is your criterion, then the "best" would be the three panels in the Kingsound King III electrostatic speaker, of course. (reviewed for Dagogo.com)