Right away I see some problems with banding and
pillow-shading through all of these sprites--problems which would show real badly against a black background. And when the ship rotates, the light even rotates with it as if it's "baked in".
These ship colors are pretty saturated as well, unusual for a space situation, where I would expect pretty much no hue shift, or a bit of a shift to blue. (You could pull off sprites with these colors though, but pillow-shading still needs to be addressed.) The latest sprites are a step up from the first versions though, but mostly detail-wise, while those other problems still persist.
EDIT:
Two quick edits actually, in two different styles just to show you some possible directions you could take. Or I might have just gotten carried away with it...
The first edit focuses more on simple shapes and the aforementioned blue shift in a duller palette, design wise it's basically a sci-fi bottle rocket, with wings.
The second focuses more on your chosen saturated palette, angles and detail, borrowing a bit from DodonPachi and other shooters in that vein--which are definitely worth looking at for reference.
Also, note how both demonstrate a clear light source, but simplified down to cylindrical bodies, with a slight cast shadow to the right. Maybe it's worth it to experiment with asymmetrical lighting?