I went for the Brotherhood of Steel, because they are an interesting faction, I liked the militaristic atmosphere and the Prydwen.
I didn't go the for the Institute because I found them boring and shallow, and not really explaining their true goals other than saying "we are humanities only hope!" over and over again.
I can't see why I would go for the Minutemen alone when I could side with them and another faction, and I don't want to help settlements.
I disliked the Railroad because they just seemed infantile.
Irwin John Finster summed it up well.
Yeah, the Prydwin swayed me as well.
Don't forget that they also literally drew a giant red line straight to their hideout and yet the scientists who can engineer synthetic people can't find them.
What?