Secret best Social Link is Ai, you'll need Courage but it is worth it.
Just enjoy the ride, don't stress over anything too much. As long as you fuse often and fight every shadow as you move up the dungeons you shouldn't run into many issues.
I think that about damn near every Social Link. But yeah, Ai has some good moments.
If I were to give Social Link tips, going for your main combat crew first helps quite a bit.
And ignore the Nurse SL, it's....yeah....just ignore it
Well, at rank 3 or 4 (can't remember specifically) it unlocks the Death link.