+1 for the Citi/Metro. If you can find a Metro, I'd say to go for that one because (as far as I remember) it comes in more sizes. I got a Metro (called the Metropolitan on the box) with the bundled accessory kit, which included the visor mirror, Mars taillight, and a snap-on rain cover. If I had to own only one helmet, it would be this one.

+1 for trying one on if possible. That's how I learned that a helmet with a pad right down the center will irritate the bump on the top of my head.