Theorycrafting suggests this which is not using StM and is showing a potential disparity of ~6.5% from the top performing legendary with 12% uptime to the bottom performing legendary. Remember the shit Blizzard got for balancing classes that could heal or tank with a 5% dps penalty? Yeah, and legendaries are causing it within specs by themselves. And you think the disparity is negligible.
The parses support exactly what the theorycrafting says. The vast majority of top parses include the wrists, the shoulders, the belt, and now sephuz. Just because a legendary shows up one or two times in the top 20 doesn't mean jack in relation to whether it's balanced or not when the ones that consistently show up show up a hell of a lot more than one or two times. That said, Blizzard did a decent job of balancing the top 5, aside from making Sephuz ridiculous for us but hell I guess that's compensation for people shitting on it all expansion.
But you believe whatever you want pal. We're gone round and round here and you think you can win. You can't. This is a discussion about balance which is entirely subjective. In my opinion, unless the legendaries that are generically useful all the time get killed in performance by the dps legendaries that are only useful in specific situations (i.e. what you dubbed as the AoE legendaries) then I'm not going to buy that they are balanced. Right now it's way too weighted on the scale so that the ones that provide universal and easy to apply damage boosts win out. Which is exactly the point I was making when I asked you about twins on the fights that it's popping up on that you oh so deftly avoided answering because it would shoot your point in the face.