Newgrounds - bigger player base, more advanced and relenting community, it really is "everything by everyone" and let's the players decide what get's the most views, is run completely by advertisements, and makes a ton of money doing so, has a great leveling system that doesn't require much thought to advance, has a great history, involved staff and the creators are constantly chatting with their fans - I've had a few conversations with Wade Fulp, myself.
Not including the choices which are better like NG is cheating. You only included krap sites in choices to make AG look better. But this IS the number 2 site there is. Whether it's a choice or not, I choose Newgrounds. Nuff said.