Well, i thought i made it pretty obvious given the vray preaching i just did. If not here it is: vray. Also, if you're not into animation, and more on the still render side, you should definitely check out keyshot. Modo has a very good renderer as well, but unfortunately i still haven't managed to get used to its interface and shading system. I find them clunky, but that's just personal bias. 3delight is also an interesting choice if you're doing animation with tons of displacement, hair, dof and motionblur, though i don't know what has been happening lately on its development front. It used to have a free license for personal use, but i can't recall if the offer was for xsi or maya. But with the xsi platform in mind, i think redshift looks really promising. Cpu's are expensive like hell. This could free up a freelancer's budget if priced accordingly, and integrated correctly.
PS. I'll share that vray vs arnold displacement test scene this weekend. See if we can get any real data. Night,
