[speedfreak]

I've seen lots of different answers to that such as

1.sends packets and whoever receives them the quickest is host
2. picks the worse connection
3. goes off upload speed

never found the right answer though judging by some recent games Ive had I think it picks those furthest away from everybody else, i.e a tent in the middle of the sahara. Does seem abit random as I was picked as host with good and bad line quality