Your sigs are all visually appealing, that's not exactly always good. It seems that your using the same style in all of them: Over-blurred C4Ds, render, monotone colors. Even pros that have defined their own style leave a lot of room to move around, change things, use different colors, different techniques, etc. The text pretty much always kills it imo. It has to fit, your doesn't, it obstructs the flow, and pretty much looks pasted on. Use blending effects, clipping masks, sub-text, and micro-shapes to try and make it fit.
As said above, you over-blur, that's not good. If you notice in "pros" work, the blurring is usually minimal, or none at all. Blurring doesn't necessarily make the depth look good, in your sigs it looks really forced by the over-blurring, and the depth-of-field is enormous. Maybe start only using about, 0.5px Gaussian, instead of whatever you are currently using.
Again, said above you use really monotone colors, in most cases on your sigs the render is the only thing that has any sort of coloration on it. The BG is usually a grayish color, and the C4Ds are usually dark gray or black.
Another thing is your focal, it's really weak. I don't know if you already do, but apply image, then sharpen, and erase everything except for the render, or objects on the same plane as the render (depth wise).