Best Ash Summons to level up for early game (Margit)? Help please.

I'm an old guy (51) who doesn't have a ton of time to play. I've played a bunch of the Souls games and Bloodborne. I'm OK at them, not great. I'm nearing when I'll be fighting Margit.

I want to level up one of my Ashes summons. I have the Wolves, The Skeletons, the Jellyfish and the Demi Humans. I am going to try to level up one of these to fight Margit. I started as Samurai (DEX & INT) and have a +4 Uchigatana and am leveling Sorcery, too, but I don't have much FP at this point. I have the talisman that increases Endurance regeneration. I'm around level 25. I'm still exploring Limgrave and the Weeping Peninsula. I'm sure there's a ton of things I haven't found there yet.

Which of these Ash Summons is the best to use against Margit in your opinion? I will probably end up summoning a player, too. I'm a weirdo: I love the Souls games but the boss battles are my least favorite part. I love these games for the exploration, the experimentation, the builds, the lore, the graphics and art direction, etc. I just don't enjoy fighting bosses. I'm not terrible at it. In Bloodborne, I managed to take down Father Gascoigne in only a few tries, for instance.

Anyway: which summons should I level up? Suggestions? Tactics? Reasons why?

Really loving this game but it intimidates me! Thanks a bunch.