With the exception of extremely limited use lenses such as the tilt-shift, you will have no issues with a shortage of fine glass for the Sony A100. I'd recommend going to a camera shop and taking a good long look at all three possibilities and deciding which one you like best. Believe me when I tell you that glass availability won't really be one of the factors to be concerned with.
Personally, I own a Maxxum 5D DSLR. There were three reasons I bought it. First, I already had some Minolta glass, as my film SLR is a Maxxum 500si. The second reason was built-in anti-shake. This saves me from paying hundreds of dollars more per lens to get the benefit of image stabilization. That's a HUGE monetary savings. Just the money I've saved in glass will allow me to buy a strobe lighting kit. The third and final reason was that I simply found the Maxxum line to be far more ergonomic and user-friendly than the competition. Within two hours of picking up the camera, I knew how to access nearly every function quickly and easily.
Don't fall victim to marketing hype, and don't make your purchasing decision based on what's popular! Make the decision based on your preference, not on what someone else might try to tell you. Or sell you, for that matter.