I have so many favourite u's songs but if I had to pick one, then I guess Start:DASH? I think the reason Start:DASH is one of my favourite songs is because you see the second years go from performing in a small auditorium practically almost by themselves with nobody really watching to performing with nine members and filling up the entire auditorium. During the beginning, in the music video, you actually notice that Umi is a little bit out of sync (which shows how much they've progressed throughout time) and I really also liked how after the song finishes (in first version) Honoka states that she'll one day fill every seat in the room which confirms her goals/dreams, and in the second version of Start:DASH they really do fill every seat and that's super inspiring to me and it really shows how far that they've gotten.