S-Corp doesn't allow multiple classes of stocks which can hinder VC funding, as they usually insist on preferential stocks of some kind...

The correct answer is it all depends on your financing plans, importance of liability protection, projected income and team makeup. Consult a lawyer.

"It depends". Search the archives - there have been lots of good discussions about this. I went for an LLC myself, and that seems to be working ok so far.

Starting as a C-corp from the beginning makes it much easier for you to take investment. If you aren't planning on doing that, though, then an LLC or S-corp are fine.