If you want something snowbally, don't learn Akali. Akali is just bad right now so if you're going to learn something brand new, don't pick her. Go Diana. Diana is like Akali, but better (Of course if you already play Akali a little then feel free since, as I said, anything can carry. She's just sub-optimal if you wanna learn something brand new)
Also, I wouldn't recommend Azir if you're focused on carrying. I mean, he's a great champ, but he needs a really good team to get proper use, something you're not gonna find in Silver
Also, if you aren't worried about bans, learn Kata or Donger. Kata is insanely good at low elo. And as long as you properly escape ganks and stun all-ins like Zed and Annie, Donger can end up being like Lb where people don't know how to deal with him. I recommend taking Heal or Barrier to be safe, not like you're often in range to Ignite. Teleport is also viable on him even mid since he's all about pushing lane... Also, last I checked (which was a couple months ago but still noteworthy since I don't think he's had any nerfs) he had a near 55% win ratio, AKA the highest at the time
Another one in the "people can't deal with" category is Malzahar. He's a lot like Donger with crazy pushing power, but instead of being an insane annoyance in sieges and lane, he has crazy splitpush and 1v1 potential (like Zed) however, he lacks escapes so splitting can be dangerous