When I make a playlist, the two things I like to think about are cohesiveness (do these songs sound good together, is there a jarring transition between tracks, do they communicate complimentary things (that can be sound, tone, genre, even a sort of consistent instrumental motif)), and texture (is this interesting, is it samey, or too easy listening)
When I think about Spotify’s daylist, it can sometimes be samey— they pick songs I like, but one after another they blend into coffeehouse music. What you have, that the algorithm will never have, is taste and an ear for the narrative of a playlist. I tend to make 8 tracks, because that’s what fit on my CDs; try starting with a track number.