Eito is a dead/missing member of the SDU for about 50% of the game (654 days or 650 if you don't include Multiple Eito since he's technically dead in that route)

Darumi is a dead/missing member of the SDU for 35% of the game (453 days)

I am almost positive that Eva surpasses both of them but I haven't counted them yet. Keep in mind this doesn't necessarily correlate to screen time; Eito and Darumi are both alive and accounted for in Romance for example but get almost no lines so don't necessarily take this as gospel for who has more presence in the game.