rizoma in my opinion... not that i have any, is overpriced.
I dunno, Monster rearsets have always been a really spendy thing, and the Rizomas for along time have been pretty on-par with the market, and when I finally got some, I have to say I find them very well thought out. Is it as neat as a eccentric-in-eccentric? No. But the adjustability seems right about the same. And on the DSS Older Monsters, its the only one that mounts to frame tabs AND crankcase (like the stock units). This provides a much more rigid platform than the standard 'hanger' design.
I'm also quite aware that my experience is only applicable to DSS Monsters of yesteryear, so the same conclusions won't necessarily apply to the 696/1100 stuff.