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
Nola Metro Grand Gold 2. Nola uses a 4 inch ribbon tweeter sourced from Raal. They reach high frequencies like I’ve never heard. Very detailed but never harsh

X3-06 EXOTIC T35

But I have heard them also with a solid copper modified baffle.
SEASExotic-T35Tweeters(CopperFaceplate)

The brass terminals were replaced with copper tubes, and the leads crimped and soldered.

1500-25KHz
Having heard several variants on plasma and ion speakers back in the very early days of HP's Absolute Sound evaluations (back when the "magazine" was little more than a dozen pages, stapled and folded). I'd have to say that they reign supreme; however, they have never been practical commercially.

Of those designs that have survived as commercial products, electrostats (martinlogan, dayton-wright, others) and magnetic ribbons (Heil, Magnepan - different, yet similar in principle) are probably the best.

I fell in love with the original CLS speakers playing string quartets when I first heard them. And, I owned a pair of Monolith III's that I bi-amped using the Dahlquist DQ-LP1 active crossover.