For free 3D engines, "the big 3" is your best bet. Project Anarchy is another but not the best looking engine out of the box. Marmoset is pretty amazing, and is probably what you're looking for. If you're just trying to show off models in a game engine.
Hey, how's it going? Firstly, I'm new here but not to modelling. I've been modelling since 2012 and I'm looking for a reasonable engine that isn't the big 3. (UDK, CE3 and Unity) I'm doing some 3D art at the moment and I'm looking for an engine to put it in to make it look beautiful (once it's unwrapped). If you are…
Maybe something along the lines of Marmoset ? I guess that's what you are looking for ( if you want to see how pretty something looks in a game engine without the need to play ) Otherwise there are shaders that work within 3D programs to make the viewport look game-like.