Gonna second that the Edelgard/Dimitri debate is stupid as hell and I like all three lords to a certain extent. Edelgard is my least fav, but I redeem her and make her likeable in my ficverse. I won't ramble here.
Also gonna add Hubert. Want to make him likable? Add endearing traits to him. Make jokes about him. Say he has red boxers and will sit in just those in his free time and smoke a cigar. Any character can be improved like this, especially ones that come off as hateable at first glance.
Cyril and Leonie suffer from the same thing, the idol worship of sorts, but you just need to look deeper and get more of their supports. Cyril's support with Lysithea is adorable, and in other supports, he drops some savage burns which are hilarious. Leonie has a nice support with Raphael, which is why I ship them.