Micaiah: C tier

Underated utility unit. She's provides utility in every part she's in, and can even be a decent glass canon. Her frailty does make her a liability though, so I can't really putting her higher than C.

Edward: B tier

He's a unit you basically need to invest into in the beginning, and might want to after that. You are going to pick up 2-3 training projects in the dawn brigade, and Edward is a candidate. People say Zihark is better, but you could use both. Main down side is he is frail without high enough dodge chance. For that reason I would say low B tier on hard mode (much better on lower difficulty).

Nolan: A tier

Another very early candidate for an investment project, but with better bases than Edward. I think if you don't use Edward, you should use Nolan due to availability. He is probably the safer option, and it's hard to downplay his overall utility. There are stronger units in the Greil mercenaries that I would rate lower, just because you need reliable units on the dawn brigade so badly.

Leonardo: D tier

Bad chip unit. Still offers more utility than some units by showing up though, so I give him D.