As SceneJS author I thought I’d throw this in if it helps: SceneJS is specialised towards fast rendering of large numbers of individually articulated objects, without game engine effects like shadows, reflections etc.
In other words it’s aimed at requirements of CAD, medical anatomy, engineering visualisations, things with 1000’s of nuts and bolts, organs etc.
It therefore has less flexibility than three.js, GLGE and PhiloGL.
It does however have a pure JSON API, which people have found integrates well with AJAX, parsers and databases (eg CouchDB).
So if you’re writing a game I would point you at one of the other frameworks, but if you’re writing a CAD viewer then SceneJS might do the trick.