LAN based or a WAN based topology
The best topology, whether it is a LAN based or a WAN based topology, is the one best suited for your environment. There is no one best topology for all situations.
mesh topology WAN
Star Topology
A mesh topology
there are a few different topologies when you are talking about WAN's but remember WAN's topologies are different than LAN's because of the area they cover. But there are bus wan, ring wan, star wan, full mesh wan, partial mesh wan, and tiered wan. as far as a drawback to bus topology is that each site in the wan bus topolgy depends on every other site in the network to transmit and receive its traffic.
Mesh topology
mesh
Full-mesh
full mesh WAN
Mesh Topology... though if you use a beefy-enough machine in the middle, a Star topology might work.
A topology is the physical configuration of a network. Each network has their own particular type of topology, with the most common being LAN or WAN. Irregular topology is a common topology of LAN, where the information is sent through random connections between computers.