Is RH the King of Disciplines? And I didn't even get invited to the coronation ceremony?
More seriously though, I kinda agree that it's probably the least build/level dependent and most universally good/great discipline. But if that's what got RH on the throne, it seems to me that in the proverbial Kingdom of Disciplines, the monarch doesn't have much real power. IOW, I think the question "what is the best discipline" is far too broad, as a meaningful answer is thankfully still specific.
Also, I think there are only a handful of RH maneuvers that actually stand out as universally great, while a large majority are just as build dependent as those of other disciplines.
Anyhow, I think for example Golden Lion, Fool's Errand and Eternal Guardian aren't far behind in terms of universally good/great maneuvers, as well as Broken Blade in its current non-errata-ed version. The three former disciplines also happen to be decently to very well balanced IMO, a parameter which I definitely think should be factored in when comparing disciplines.