Should I level Medusa Lily, Marie Or Astolfo?

well i'll personally go wth medea lily .She can be used in many gimmick fights and she is the most relevant between those 3.

That being said ,if you like traps then astolfo is your guy.

If none of them interests you, save exp cards for MHX alter. Who knows u might get her with 1 tix.

If it was me, I would go with Medusa.

But that is because I am trying to create a support group of Medusa Lily, her sisters, and every young female servant I can get (like Medea lily) so that I can name it “the LOLIpop gang.”

Medusa would be my (unbiased) answer.

I'd go with Medusa Lily because she's a cutie.

Really though Astolfo will get a huge NP battery that will make him pretty useful.

All of them are pretty meh. Marie has her niche if you enjoy stalling and/or need a rider equivalent to Cu Chulainn.

All of them is a disabler and each one have good survivability, to be exactly they're best suited as a backliner.

Astolfo : 3 Times Evade ( NP ) + Stun
Medusa Loli : Invincibility 1 time + Guts + Stun ( NP ) + Charm ( males ).
Rider Marie : Invincibility 3 times + Charm ( males ) + Heal + heal + remove debuffs.

Their kit almost have no offensive skill, they're geared towards survivability for harder contents and annoying enemies ( Alstolfo is pretty strong on JP but on NA now, still meh ).

Astolfo and Medusa Loli only have 1 Atk up skill with 1 turn CD...............i've mentioned before, they're a survival based servants. Astolfo Offensive skill is not too reliable, chance to buff for 65 % for each turn for each buffs, his strongest trump card is his Evade and staying power and not his Offensive buffs.

I would suggest Marie or Medusa Loli for now if you're lacking some tough servants, Marie can also act as a daily farmer so level her first because you farm everydays.
She will also receive her strengthenings soon, it increase her Crit damage and heals allowing her to stay on the field even longer and kill her enemies even faster. She's also a rider ( Archer + Rider is a Crit stars magnet ) which means she would appreciate the Crit damage buffs.

Marie is basically a Chu Rider.