alright...all immature jokes aside, the third one needs serious work. From a purely visual standpoint, the lower strut on that one is very un-balancing to the design, as it draws focus away from the main hull of the ship (despite being phallic). It is also relatively un-detailed, and seems to serve no real purpose at all. In the other two ships, their verticle fin/protrusions had some function/detail. I thought the little lower fins looked cool. And the other one has an engine on the lower part, which would look awesome flying. However the 3rd one's serves no real purpose and is intrusive on the design. It also looks slow and lumbering. More like a bomber than an elite fighter. In fact if you put missile bays on the sides of that protrusion (lower down to avoid more jokes, and perhaps thin it up a bit on the bottom too), it'd make a cool medium bomber.
Also, although you may not give a rip weither your ship has a giant wang, remember that ultamately we (the members of the FS2 community) are your audience, and do you really want to remember CIM as that one campaign with the ships with the wangs?