Default to USA.
Most of the site traffic will come from the USA. That should be the default country in the drop-down menu.
Goran Gligorin commented
You should have some subset of popular countries at the top and if you can get the user's current country add that one in there as well.
Matthew Hintzen commented
Yeah, the default should be based on the Culture Selection in the browser at a bare minimum, Country IP location if possible, but as a ex-pat Yank, may I say, the USA doesn't need anymore press for presumption of Primary Importance!
Adminshanselman (Admin, nerddinner) commented
Totally. On the roadmap.
Chris McGrath commented
something more interesting for this wwhich is hardly seen would to guess the default country by ip