Atl - Retire
BGs - Retire
SF1 - Definitely RETIRE Alef, Balbaroy, Bleu, Gong, Gort, Guntz, and Zylo. PCs with little plot and/or aren't widely used and/or are even more subject to RNG than normal for worth.
For now, abstain on Anri, Domingo, Lowe, Mae, Tao (more used/notable/popular), and all the bosses.
SF2 - Definitely RETIRE Chaz, Elric, Galam, Gerhalt, Kiwi, LEMON, Luke, May, Rohde, Zeon, and Zynk. Optional/less used/less notable/less early PCs and bosses that nobody cares about.
Abstain on Cameela, Chester, Geshp, Jaha, Kazin, Sarah, Sheela, Slade, Taya, and Zalbard. More notable bosses (with history in some cases), and early/more plot important/more notable PCs. Could certainly be argued on some of those PCs - Sheela, Taya, and Jaha in particular.
Retire Rassius. Abstain on Shizel. Keep the PCs.
Retire Freya.
EDIT: All SFs I abstained on are now Keeps.