monochrome is probably the big one aside from Trauma. They all kind of shared the spotlight though. I would say the one given least recognition seems to be too late.
monochrome also got voted in by fans to be on A SUMMER BEST over the other three tracks.
I think the single to Ayu represented a time when she may have wanted to quit being a singer, so aside from Trauma which sort of forced itself into concerts, the rest of the songs are not performed as much due to the memories associated with them.
When people had the opportunity to vote for songs to get into A BEST LIVE they also voted for Trauma / End roll / monochrome but kind of ignored too late.