How many antennas do you use to cover 30 miles? 802.11 isn’t designed to cover long-range applications. If you do want to cover a 30 mile radius reliably, you’d need a mesh network with hundreds of access points to reach acceptable performance.
I guess you need to pick your access points now. To build a strong wireless network for general use, antenna matters, but solid access points matter even more. You need solid access points that can be firmware upgraded to ratified WiMAX standard in the future.