Sol - By far the #1 priority for Light users. All of her skills are highly useful. Most importantly, her ATK debuff is C Frame, making her irreplaceable in most situations. Future meta - in June+ 2019, the meta may become more offensive oriented, endgame teams might go without healers. Until then, Sol has a role in your team.
Note that in general, other than Sol, defensive himes have lower priority than offensive himes (above) - this is important to note when using miracle tickets.
Eros - For defensive builds. Her 20% ATK down is the best after Sol. However... see Raphael below.
Raphael - Like Eros, she provides ATK down, but only 15%, which makes her the inferior choice. That is until she gets awakening in June 2019, at which point she will get Overdrive Reduction AND Overdrive Extension, making her nearly broken.
WARNING: FOR NEW PLAYERS, IF YOU DID NOT ROLL EITHER MICHAEL OR SOL, YOU SHOULD REROLL YOUR ACCOUNT (unless you roll the 100% Light Eido)