Like mentioned above, these are all entry-level mountain bikes. Again, they're much better than any "X-Mart" bike, but at these low prices, it's hard for one manufacturer to do anything really different from his competitors, (The margins are much smaller the less expensive the bike), so you will find many of the same components, frame material, front suspension...etc.

The biggest difference of bikes at this level are frame geometries and paint schemes.

I highly suggest you test ride each of the four bikes at least once more each. Decide which one is the most comfortable for you. Buy that one!

L8R