The Viva Audio Nuda horn system knocked my socks off at HiFi Deluxe in Munich this year. I'm still thinking about how it sounded on opera, and what I'll have to do to get my own designs to get there/beat that. I haven't heard the Viva Audio Masterhorn, but if the designer Amadeo is to be believed, and he tells me that the Masterhorn is even better, that might be the horn loudspeaker to beat.
I believe you! But I have to draw a line somewhere.
My natural preference is not toward dynamic driver systems. But in that genre the Rockport Arrakis and the VSA VR-11SE Mk. II are my personal nominees.