I dont like any of their title tracks, they're all blops or flops for me. But Panorama i think had the coolest looking MV and second best choreo while Fiesta had the overall best choreo. Violetta is probably their best title track and closest to a bop.
I like many of their titles though. Violeta is unfortunately my least fav song but the MV is really good. Fiesta and La Vie En Rose are my favs but I gotta give it to Panorama for the MV. Fiesta is a super close second.