That really depends on your map size, TFS version, the expected number of players and your experience.
This question has been posted/answered so many times here on the forum just search around and you'll find all information you seek.
otland.net
otland.net
I can just give you a small tip when choosing your host, first get to know your players base because most of players will only care about their in-game ping.
If it is like Brazil/South america players then you can choose Canada hosts.
If it is Europe players then you'll have to choose any Europe hosts (France/German).
You can also read this thread...