First one = Saggy tits and text is disproportionate to the graphic.
Second = Good concept but probably doesn't need the graphic as the text is unique enough.
Third = The Es and Fs are identical. Manually alter them to make them unique.
Fourth = I see what you did there. Colours need more contrast.
1) Type too small
2) Like it but not sure of the relevance of the symbol with the type
3) Nice but maybe tighten it up a little
4) Need a better choice of colours - the foremost blue is lost against the dark grey
I am guessing there have been done for your own pleasure/portfolio - pretty good, with a few tweaks they should look sweet