For 71-80, AV is the only way to level. I started 68 in AV and the xp sucked ... soon as I hit 71, it was WAY more. I did 71-80 in a week ... few hours a night. Getting a third team of 5 to 80 now. If you win 80% games, you'll do it faster. It's WAY faster than questing. Everyone is talking about an incoming nerf to AV xp this tuesday b/c it's so good (but haven't seen a blue post on it yet).