-Ahri is in a very good spot. Has medium ratios, gets pretty mana hungry as she levels up. Low movement speed as a trade off for the mobility that comes with her kit. She generally cant 100-0 another champ unless fed, as she requires a poke mage playstyle before she can commit to an all-in. A lot of her matchups are skill matchups. Can be outplayed just as much as she can outplay someone else. Has great early and mid game, but can have a hard time late game.
-Akali has the absolute worst laning phase, just trying to farm up until 6. She has heavy snowball potential, but is far from a safe pick.
-Yi goes either way. He can be absolutely crushed or dominates his lane. has only one 'true' offensive ability (but has very supplementary abilities to compensate). Can snowball to hell and back if you let him, though.
-Leblanc..... well she's a huge bitch and everyone knows that. Not a whole lot to say about her besides the fact that she's an early game monster and she has some mechanics that should be fixed.
-Kha'zix seems like a very weak and strong assassin at the same time. Hardly ever see him used anymore, so I cant actually talk about him. I remember him being used a lot last season, though.
Lastly, it's not that zed is too strong, per se, it's that he's extremely safe during his laning phase, sort of like leblanc-except even safer. If you manage to die a lot with him in laning phase you're probably an idiot. (not pointing fingers at anyone here, just generally speaking.)