The best tweeter design


Been giving some thought on the best tweeter design and I came up with the following list:

1) Plasma
2) Ribbon
3) Horn-loaded
4) Diamond dome
5) Ring radiator
6) Inverted dome

But since 1-3 are hard to implement or expensive most speakers start at #4, at best.

Thoughts?
cdc
It is my own experience that implementation is at least as important as tweeter type. I have used Ionic, ribbon, and many different types of domes. The first two have many virtues but are hard to match with standard cone speakers. I have tried titanium domes and find I prefer soft domes to them; this is a personal choice, not "better" or "worse". As I like Scanspeak I decided to try some speakers with the "Revelator" tweeters, I have purchased some but not yet received them.
I LOVE the Raven ribbon tweeter in my Alon apeakers mated with the Seas Excel Magnesium drivers
So far one of the best I have seen is the new tweeter made by High Emotion Audio http://www.highemotionaudio.com.

It is high efficiency, very fast but smooth without brightness and extremely wide dispersion angles (120 degrees). It is also rear-firing and crosses over at about 2KHz. It surpasses any ribbon I've heard (for example the Raal) and ESLs. They have at least two patents on it as far as I know.

The only other tweeter that I have heard that is as fast (but much more limited dispersion angle) is the field-coil powered tweeter made by Classic Audio Loudspeakers.