I love the look of the Bessaflex, especially in silver, but beware that there's no flash shoe on either the black or silver cameras. If there was, I'd probably already own a silver Bessaflex. As it it, I'm considering an old Spotmatic for a cheap-lens camera.
On the Nikon side, the FM2 has most of the features of the FM3a, and can be had for a whole lot less money. The shutter is fully manual, so the battery's only needed for the meter. The FE2 needs the battery for almost everything, limiting you to one speed (1/90th?) if your battery dies. If you go for the previous generation of Nikons (FE/FM rather than FE2/FM2), you get a slower shutter and no flash automation, but you gain the ability to use the pre-AI lenses. Pre-AI Nikon lenses tend to be very cheap. You might want to look into a used FM and some pre-AI lenses...you might be pleasantly surprised at how inexpensive a flexible setup can be. The same can be said of the old Nikkormat cameras, depending on what sort of metering options you need. All of the cameras I noted that can take the pre-AI lenses can also use the AI and AI-s lenses as well. (If flash is important to you, then the FE2 is hard to beat.)
One other note regarding the FE2: I mentioned that the camera's virtually useless without batteries. The batteries are, however, very small and it's easy to carry a spare set with you. Plus they last a very long time. I've had an FE2 since they first hit the market, and I've never actually had the batteries die on me. I always replace them after a year regardless of what state they're in (I hate the though of batteries leaking in a camera), and I've never had a set die on me. So the battery issue isn't too important with the FE2.
Best of luck with your decision.