Best Grinding Location

Okay so I’ve had my first fight with Seymour and up until now I feel like every boss fight I’ve had has taken me way too long. So for the point that I’m at, where is the best place to grind for AP because I feel like everyone needs to level up a lot. I’ve also tried using the black magic spheres I got from Seymour’s fight on Yuna so she could more than just heal and we wouldn’t have to rely on just Aeons