I voted loose affiliation, as it's the general mode that a majority of my campaigns have started under. In general, most players seem to find that way fairly easy to go with, and from a roleplaying standpoint, it cuts down on long lengthy introductions and awkward periods of getting to know each other.
When using the options where they don't know each other, I've actually seen characters fight one another in the very first session, or just refuse to team up, calling it "in character". Not a great way to start a campaign, when it degrades into a pissing contest between PCs.
At least I don't resort to the "you meet at the tavern" cliche intro. Instead, I usually have the characters share some element in their recent past or present such as sharing the same employer, customers of the same shop, friends of a missing person, etc. While those can be equally simple, it's at least an improvement, IMHO.