I have thrown several hundred dollars at WiFi equipment, cable, and fittings.
The cleanest and most reliable system that I have used to date is the RadioLabs WaveRV antenna. This antenna will draw in wifi systems from a mile away. This antenna alone worked very well, but the only downfall of the system is that we have an outside USB connection in the system, and this has been a problem spot for us.
I just ordered another RadioLabs antenna, the GS-2400 -High Speed Wireless Bridge. This is a different antenna that is powered through the network cabling, and has cabling limits of 165 feet of length, with no exposed connectors. The new antenna will be directional, and should be easy to aim, but time will tell.
Attached photos of the existing system.