1. I'd like to see some of the more broken units get nerfed a ton, it's a lot of fun getting over 100 crit with Rutger, but it is definitely game breaking. With this in mind I'd nerf a lot of the bosses as well, since sometimes it feels as if using the broken units is the only way to beat them(or I'm just bad at FE :P), the way I'd do this is probably just decreasing throne bonuses since some of the faster bosses are impossible to hit.
2. I'd like to see something reminiscent of SoV's animations, they're quick and a bunch of fun to watch.
3. To be honest, I wouldn't like to see some of the bad units get buffed. Some of my favorite memories with this game are mostly me training up a unit like Sophia. I feel like its realistic in a way that some people are just outright stronger than others.