Should I buy Syndra or Ahri?

Well, Syndra is obscenely overpowered and Ahri is not.

Ahri is a champ who scales well into the mid game and can't really get behind. Her Q's true damage return is always useful. Her charm is an extremely strong pick CC and her ulti makes her extremely safe, which means post-6, you shouldn't really be getting caught and dying too often. She's easily the safest pick for any mid laner and can absolutely ruin worlds when she gets fed since she essentially vomits her cooldowns and instakills anyone she catches with her charm.

Syndra is a late-game bully. She's the mage which you get stunned by and instantly get deleted and there's nothing you can do about it. Great peel, so she's never really useless when behind and I think she's also an extremely safe pick.

They're both pretty even, but Ahri is a bit easier where as Syndra just does more damage late game.

Do you prefer Thighs or do you prefer feline ears and nine feline tails?

Syndra is hard. Really hard. You have to know how the physics engine in League works, which is no easy task. But once you learn her quirks, her damage potential is unreal.

Ahri is probably easier for you to learn and is still quite strong, but Syndra is more skill based, and naturally stronger.

Both are pretty heavy on the burst scale but Ahri is slightly less burst and slightly more sustained damage.

Ahri also has a bit of health sustain and decent mobility built into her kit.

Syndra has self peel but low mobility

Ahri has better catch potential, but Syndra has better zone.

Since I don't know your skills or preferred play style, I would always recommend Ahri over Syndra simply because ease of use makes for better buys. People are less likely to abandon a champion that they can learn quickly. However, if you like to challenge yourself, learn a champion thoroughly, and hard carry, go with Syndra.

Why play ahri or syndra when you can play Hybrid bluesuo?

Pick the one you actually like the abilities of, if you're buying syndra because worlds forget it. You will be bored of her in 2 weeks or something. Ahri is kind of the same way, most people think about buying her because she can almost always be picked. If you don't really like both champs buy the one that's most popular atm just for trading in champ select. I think syndra is the more common one now.

ahri