second to last is pretty cool. you just need to learn incorporate flow, composition and depth into your effects. you cant just have them all over the place. also work on colours and lighting/contrast. also use better stocks/renders.
You biggest problem is lack of color and depth. First and last (imo) are the best, but they lack any dimensions and color palette. Try and incorporating colors instead of taking the hue away and gradient mapping the whole thing
By using light and shadowing to create a 3d landscape. Also by using depth of field to create a sense of space within the tag.
No you need to move away from smudging the hell out everything. That is a beginner technique and you should start learning how to create a tag without having to smudge everything to death because first it is hard to create a lot of depth with smudging only. Second it is very difficult to get rid of that messy feel.
Well I have seen some really good tags that have the same technicue and they look really sweet. The reason I dont wan't to do C4D signatures is, because I don't like them. They look way too messy for me.
Smudging can make good tags, but you have to have good technique, colors, and settings. When you say C4D tags do you mean C4D text tags or tags that use C4D renders? Because C4Ds really help build spacial orientation inside of a piece. They help give points of reference and force light and shadow if done right. You don't have to put 30 C4Ds in a tag on overlay. One or two C4Ds to help with the flow, depth, and lighting is plenty.
#5 is the best sig out of all. You still need to read up some tutorials. It's still grainy and a lot of your signatures are spammed with fractals, if not random smudging that's everywhere. Practice your smudging to give it more of a distinctive style to it, that's eye catching to an audience.