I prefer the characters in Golden Deer

So why do I always end up choosing Black Eagles every time I replay this game

Probably because it's the most unique storyline, considering it has less crossover with the other paths (assuming you do the CF route) than all the other paths have with each other.

Also because it has less chapters (on the CF route), it's quicker to beat it and move onto another playthrough using different characters.

Oh its shorter? I forgot. I havent played in over a year. Im trying to recruit everyone which I was able to do last year but it took a lot of planning.

Edelgard was right and the world needed a purge.