Champions are roughly ordered in strength within each tier from left to right.
Yasuo: Decent pick on his own, but significantly stronger with certain supports such as Gragas.
Cassiopeia: Much better into shorter range ADCs (Kaisa, Xayah, Jhin) than longer range ones.
Syndra: Strong counterpick into Heimerdinger, kinda mediocre otherwise.
Made by the collective efforts of various r/summonerschool Discord Mentors