I like #2 and #4. But they are only good if they fit you. At 25 inches, #4 is a really big bike.
Read up on bike fit, then take bikes for a 1/2 to 1 hour test ride before you put your money down.

Fit is really important. If a bike doesn't fit, it won't feel good to ride and then you won't ride it.

I think you strategy of buying a good used bike rather than a Wallmart bike is really wise. I've bought as many bikes used as new, and there is a certain satisfaction from resurrecting a good bike. Finding a specialized rockhopper with full LX group for $150 and finding a Miyata 1000 for $80 has made a couple of friends very happy.