Open Shortest Path First (OSPF) is the best choice for an enterprise network spanning multiple geographic locations due to its support for large and complex topologies and its vendor-neutral specification, which ensures interoperability among different vendors' equipment. While EIGRP also supports large networks, it is less ideal in environments that require vendor interoperability since it is Cisco proprietary, potentially limiting its use with equipment from other vendors. BGP is generally used for Internet routing between autonomous systems rather than internal enterprise networks, and RIP's limitations in scalability make it unsuitable for large networks.