I think I will just use the 600px1 and 600px2 (the first two pictures)
But maybe in bigger size (something like 1000px wide) + credits
Because 600px is tiny (I made some test, look tiny on most forums) and it make your work less impressive I think
Also the rendertime is not for the 600px but for the 1280px so that will confuse people
Could you post those two in 1000px by X ?
1280 by 640 is too much in horizontal size (1280 too much for some screens)
I think the second series with the jewel are much better in high res (because of the ammount of dark)
But the robotic things look better, that's just my personal taste in robots
