Which 5 star exclusives should I focus on for each color?

For each color, here are the units I'm missing that are in the normal summoning pool (units I haven't listed are either seasonal or I already have them):

Red - Saber, Zelgius, Leif, Karla, Laevatein, Adrift Camilla

Blue - Hardin, Quan, Kliff, Adrift Corrin (M), Ylgr

Green - Olwen (WoT), Heldbindi, Adrift Corrin (F), Surtr

Colorless - Faye, Maribelle, Loki, Mikoto