I thought I responded, I must have closed the browser when I left for a meeting instead of posting...

Anyway the core of my guidance is this:

As long as you avoid the department and discount stores, and buy from a bike shop, you will do just fine.

Each manufacturer's bikes at similar prices will be of similar quality. The manufacturers will each make slightly different decisions on components, etc, but basically test ride a few, and pick the one you like riding the best. Make sure that you don't choose based on a minor adjustment tweak, see if the shop will tweak it and let you test ride again. But other than that, buy whatever you enjoy most when you ride it.

If you can't tell the difference in ride, pick based on which shop you like best. If the shops are all good, then pick the one that is the prettiest color.

As far as the specific bikes you list, I would just suggest that unless you plan to ride dirt trails and do real mountain bike stuff, I would lean toward the bikes with the 700c wheels, unless you are short. If you are short, the 26" bikes might be a little better because of the smaller wheels matching the small frame.

The 700c is just my own personal leanings since the 700c bikes seem to be designed more toward paved usage, and the 26" bikes are set up a bit more toward mountain bike usage..