What would you recommend as the current best choice for an open source 3D rendering engine (need not be a full game engine) with a "modern" mindset ie. is shader-based, and uses rendering APIs in a non-deprecated way?

IMHO all of the usual, well-known candidates have fallen behind one way or another, for example OGRE by not being terribly CPU or GPU effective and in need of a general cleanup; the current active developers themselves point this out: http://www.ogre3d.or...30250&start=154, or Crystal Space & OpenSceneGraph by always having been cumbersome and/or unfriendly to begin with.

I'm not really looking for a solution for myself, but just want to encourage discussion if there is some excellent library/engine out there we are not generally aware of?

(for what it's worth, I personally use OGRE & Unity (which of course isn't open source) at work, and then I have my own hobby engine which is D3D9/OpenGL 2.0 and MIT licensed -- link is in my profile -- but it's as of yet unproven for any larger applications, and lacks features, such as terrain rendering)

Last time I touched Ogre (2-3 years ago) it possessed very competent terrain rendering capabilities. If anything, it's engineered quite brilliantly; I'm sure with minor investigation to see its current state, I would recommend it again.