The game is very busy (MT4). I wouldn't pick a large hub city, but maybe a medium city to start with. A good airline can actually be based anywhere with the right planes and enough traffic. I think North America would be a poor choice just now, and Europe too. Perhaps Asia, South America, Australia, perhaps? I'm not sure, its just that North America and Europe are quickly taken. Or as the other person said, wait for the next Jet Age game.