The best tweeter design

Wesexias I have the Acapella plasma tweeter in my system, and a friend has a Lansche Corona plasma tweeter. IOW - I have heard both plasma tweeters which are currently in production.

If I had to pick a second best, I would nominate the Heil AMT (as used in Adam Tensor speakers) as a superb tweeter. Extended, uncoloured, free of any metallic sound, and natural.

I greatly enjoy speakers with paper cone tweeters.

Electrostat is the best form of tweeters I have ever heard. Better than ribbon or any such planar design.

Among the conventional tweeters, Esotar is the most revealing yet natural sounding tweeters I have come across.

I used to agree with Amfibius about plasma tweeters. I have since bought Tidal speakers with a 1" diamond tweeter. I clearly is better and also expensive, however.

I know it doesn't seem to make any sense that a tweeter with mass would sound better than one with none, but I do find this. I think it may be the power supply that is needed with all plasma tweeters.

I've been speaker building for 32 years. The best tweeter that I've ever heard is the old Hill Plasmatronics.
I've had great success with ribbons, but they can be beamy and one that can cross low is expensive.
Horn loads: (you can hear the horn)
Diamond dome:(Accuton) Haven't tried them... I'm always on a budget
Ring Radiator: (old advents) ok
Inverted Dome: (Focal) Fast, Detailed, can sound etched & grainy easily with some electronics, wonderful with others.
Soft Domes: I currently use a Scan Speak with excellent results. Alot of variations with very different outcomes.
Bottom Line, use a technology correctly and you can come up with a very nice sounding speaker.