If both these AP's are running unstable, there must be a reason for it! Did you check for interference?
You can have the best AP in the world.. if there is interference, you will never have a stable connection..
First investigate what happens before judging the AP itself. Start bij checking the noise and signal levels on both AP and client. This will give you a rough idea of how much interference there is.
Also, if you want some help, it would help if you give more technical information..