The rendering is really improving.
Would these suggestions be welcome?
The background "merges" a bit with the object.
You may need 2 or 3 lights(Did you have 2?)---each with a different "strength"
(If you could download or PM that last file (.obj) I could maybe (!) show better what I mean.

There is no "right" answer--lots of learning if you just take time to think of all sorts of alternatives and try them out.
What rendering app do you use?

Brian

ps. The attached shows just one lot of "inbuilt" lighting settings in Carrara. I have circled to show a whole lot of additional ones!
Choices, choices, choices!