Which (capacitor, wire...) is best?

The best—it doesn’t get any better. But better for what application and better in what ways? All tweeters, all capacitors, all components sound different. Fitting a part within a design is a systematic choice, one might be good for one system or circuit and not for another and to what end is most relevant. After all, your priorities within playback my not be ours. Loudspeaker systems are just that—systems. It's like saying one capacitor is definitively better, the kind of thing we all see frequently in hi-fi audio discussions. Tweeters, like caps, like wire, like everything have application within a system and true of all parts and subassemblies. There are no absolute “bests”. There are however plenty of biggests, most expensivests, heaviests, loudests....

In hi-fi we take our sound so seriously that we usually cripple it. Hi-fi freaks like you and me needs to follow the lead of the musicians—there is no best guitar, no best sound or melody or rhythm.... Our musician buddy Dan Weldon comes in the shop from time to time, usually when he needs a tone fix, sometimes to take us to lunch. He’ll have a box of a bunch of some thing, and the guitar he’s currently lifting deeper tone from. Conversation usually goes like this, “I’m looking for more (insert some aspect of tone he is huntin’ for, always specific to the guitar and what he is going to use it for) and I’ve tried a hundred combinations of these widgets and found the perfect combination. The tone I’m getting is killer, check it out.” He plays some stuff through the whatever the system of tone is, looks up with a big huge smile, “Pretty sick isn’t it. Best tone yet...” then he goes on for at least five minutes, usually much longer, qualifying what he’s going to do with that sound he’s found, how he will use it and when, at what level, where.... Bests are contextual.