The first one is wayy to blurry. You need to sharpen parts other than the render, otherwise it just looks like sloppy DOF.
Not bad colroing though, work on your compo though seems liek your forgettign the rule of thirds.

The second sig is cool, great compo, decent effects though they look a bit weird. I just wish the rock was a bti sharper.

3rd is decent but that c4d rly detracts from the focal and looks really weird.