I may not be an expert but ...
I do not know a hell of a lot about proportion but I can tell you the first painting looks a lot "correct" visually than the other two. Sorry if that does not help a lot but I wanted to give you an honest visual report. I think the painting is awesome. Great use of color and definition.
You say its too fantastic that it cannot be true
But I say that can happen and it can happen to you
One minute you'll be thinking that everything's fine
The next thing you know well you're there with your heart on the line
There she goes
There in the moonlight
Under the stars
Tarantula -- Bob S.