The brushing and BG work on all of them is pretty nice. Though the text in all of them is pretty poor :-/
I think the text could be worked on. Having said that I seem to find myself saying that to most people. The brushing, colouring & blending are all fantastic. I especially like 1,2 & 5. Great work m8
I think that all your sigs are too similar - like they all ahve a render in the middle or to the right and have text on the left. Also you need to work on your etxt. Good brushing though. 7/10 over all