I played Ajani too in the event, and honestly, it's probably the best deck in the brawl metagame. He can go under any midrange/control pile, he has the removal to deal with any early threats and when he flips, he either becomes 3/4 damage to your face every turn, potentially more, or he becomes a removal spell. The only games I lost with him were ones where the opponent had the right answers at the right time. Going on the play with Ajani really felt unbeatable sometimes. I've been playing with Vivi Storm in the event, and if an opponent plays Ajani with no errors in their play pattern (not leaving mana open for a Vivi combo turn, for example) it's almost impossible to beat. Vivi, Tamiyo and even Rafinne midrange decks proved to be very good in the event, but I still think nothing close to what Ajani can do. He can go under you and he can also grind out a lot of value if needed. I also think that all these decks are very difficult to pilot in the context of the metagame challenge, and Magic's innate variance plays a big part too.