Wireless coverage will vary with the conditions of the installed environment, as well as the quality, transmit power, and receive sensitivity of the radios hosting or connecting to the wireless network. Open-air with no physical obstructions is obviously going to net the best performance/range, but most of us don't live and work outdoors, on a desert plateau. So, choosing which wireless access point and where to install it is not simply a matter of which access point has greatest range. With proper care and feeding, most access points can serve well in a typical home or small office environment, but when the building is complex or large this is when we run into trouble.
If you could be more specific with your inquiry and provide some details about installation environment I'd be glad to answer any questions you have.