The best meta champ ?

Mid I would have to say Zed or Galio atm
ADC: Ashe & Ezreal are super good picks
Support I would say Lulu or Senna
Jungle is Graves and Lee Sin and they are very strong picks
Top meta champ would be Darius (he has been meta for a while)

MD: Akali, Katarina, Ekko, Fizz, Diana, Yasuo, Zed, Galio,
SOLO: Fiora , Darius, Garen, Urgot, Mordekaiser, Nasus, Sett, Fiora, Jax
JUNGLE: Sejuani, Ekko, Amumu, Warwick, Zac, Shaco, Lee sin, Graves, Elise
ADC: Vayne, Caitlyn, Jinx, ,Ezreal,Ashe Jhin
SUP: Thresh, Blitzcrank,LuLu,Brand,Senna, Soraka, Alistar

It's useless to worry about things that already happened and cannot be changed.

Always play flex picks so you dont need to learn to much champs

Mid: Zoe
ADC: Ashe
Supp: Naut
Jgl : MasterYI
top: Garen

Mid: Zzed
ADC: Ashe
Supp: Naut
Jgl : MasterYI
top: Garen

Top, maybe Aatrox or Fiora.
Jungle: Lee sin is always Meta.
Mid: Yone is really good.
ADC: Caitlyn is very strong not overpowered and shes always meta as well.
Support: Definitely sona, if u build tear first.

Mid: Zed/Ekko
Jungle: Shyv/Kha
Top: Darius/Malphite/Sett
Bot: Ez/Kaisa/Xayah
Sup: Thresh/Naut/Panth(surprising)

Supp: Yuumi or Nautilus. Should be first ban always