Very nice modelling, and I really like your lighting and composition in your second version. I think with this being a concept design it comes off really well on the white background. If you want to put it in an environment, I would suggest having it in the air rather than in a hanger. In terms of CG stuff, they only comment I have is that the nose looks a little grainy and flat. I don’t think its your samples, since the rest of it looks great, but you might try playing with your shaders and lighting in that area.
From a design perspective, a couple things stand out to me. Now, I’m no aerospace engineer, but the fans (which I assume are for vertical takeoff) seem too small to lift the plane. The wings also seem a little small (width-wise) to generate enough lift, and they seem a little far back, which makes me think it would be unbalanced.
Otherwise, great render and cool design idea!