I like the last one the most.
The first one has a good concept, but those arc's need to be way bigger. They just seem a redundancy to have a thin structure go out like that.
And they all still look part terran-ish.
If your going for a new design, throw somethings in there that havn't been done before or are rare.
Like thrusters not at the back of the ship, midway or near the front. Other assorted design mechanisms as well.
Try and pick a similar theme that they all stick too.
Those four do have a theme, but at the moment its that they are all 'box like'.
But yeah, keep em coming.
