#30 and #37 - I like the orange color, a part of the brief that seems to have been overlooked by many designs. I like the 3D aspect. I'm not so sure about the connotation with a screw (i.e. screwing clients!?!). I like the dot over the "i" as orange in #37.
#41 - I like this. The image of a cog, while not that of optimization, is a nice one. The orange is good - maybe the blue could be more of a navy blue.