Entwine
But my real answer is a cop out: It Depends. They're both cards that are best suited for ramp strategies, so it's more a function of how many Sakura Tribe Elders, Explores, and Oracle of Mul Dayas you run. If you have 20+ green cards that generate mana (like I do in my cube), Avenger of Zendikar in particular is supreme. I personally think it's ok for a seven drop to be difficult to answer by anything other than Day of Judgment, because heck, it's seven mana (and really, eight before they get more than 5 power out of the card).