using the 3d stuff is a nice touch, but you haven't pulled it off very well.
like with the purple one, the text doesn't fit in the thing correctly

the red just looks a bit weird, because it's got the whole minimalistic flat-shaded 3d thing going on, while having loads of polygons (i.e., not the minimal amount)
orange looks weird, how the changes in shading are just rectangular sections, and the font is all serifed and the text doesn't align to the edges of the surfaces correctly, as well as blending into the part it's on a bit (making it harder to read)
blue is just a bit weird, especially whatever it is you've done with the text. the colours don't really complement each other or make for a nice composition.
the visual styles of all of this stuff really just seem to be inelegant and sloppy, really. Green doesn't really forget much up: the texture is nice and the whole "planty" element to it works well.
it's nice to experiment with what you have to work with, but it can really help if you pretend like you're making it for something, like a logo or a game thing, or just art. although typography (for some people) is art, its mostly used to communicate things blatantly, as opposed to the more ordinary kind of art, which is more about subtlety.
hope i wasn't too much of a constricted sphincter and that you can take something from my gabber