CLAMP have always been about flamboyant styles, dominant to the eye costume (mecha, props in general) design, the characters are only detailed in hair (though that isn't unique and quite common, it's done moreso).
The styles of Akagi and Kaiji are specifically designed for the feel of the demography (just like shoujo), the people who like the "hard" or "real" (as in symbolically real, that style pulls off "manly composed smoker" better than CLAMP, for example) will like that style.
We all know Key is fucking down syndrome moe shit, nothing can redeem it, but it doesn't need to be, it suits the garbage that comes with it.
imo, one piece is very.... loose, it follows the ideas of Disney in it's basics, nto much else to be said, either you like it or not.
The rest of the styles are just revamped generic anime styles with slight differences.
Each serve a purpose, each have appeal of their own.
Well, opinion, your, etc..