So, after playing against Zed, LeBlanc, Talon and Katarina a few times as both mana and manaless champion, I can say a few things about these match-ups.
As a mana champ, LeBlanc and Talon felt quite good, attrition fights, who runs out of mana first for pushing and making mistakes, while Kat, having her short ranges wasn't a problem.
As for Zed? He felt unfair from the get go. As a mana champ, if I need mana and expend it a lot (champs like Taliyah), then Zed has an unfair advantage from the go because I'm in a lose-lose situation just because he's Zed. He has energy but has quite high ranges so he can shove decently but because he is Zed, I need to rush an Armguard unless he's a complete moron, but as a mana champion, that hinders me in a different way, as I have no form of big mana recovery, aka, my Lost Chapter, so even if Zed can't kill me, he can still force me out of lane simply by shoving the lane, as he regains his whole energy between waves, assuming he used it all (suuuuuuuure, at those cooldowns?). But if I don't get the Armguard and get the Chapter, then I don't have enough armor to defend against his WEQ combo as well putting me in a prime position to be killed by him.
As manaless champ, Talon, LeBlanc and Katarina were interesting match-ups, Kat feeling as quite a skill match up, LeBlanc was basically a "who fucks first" while Talon felt to be in my favor but not by a large extent due to me being melee with short ranges (I played Kat and Akali).
As for Zed? He felt fair for once, I could match his shove and if I didn't screw up, he needed to start playing actually smart instead of the normal WEQ half your health or mindless push he does.
Zed's energy base and the fact that mages need to get an Armguard against him gives him a huge advantage in uncoordinated solo que, as the mage needs help from the jungler to keep Zed on the back foot but if that doesn't happen, Zed simply "wins" the lane by having better recall timers, better farm and better roam opportunities (let's be honest, what does a mage with no mana and a wave crashing in his tower get from trying to chase the Zed's roam beside a grey screen?), while if the mage doesn't get the Armguard, Zed has quite high kill pressure due to Lethality.
So my question is, what if Zed had mana instead of energy?
That way, a mage can chose between Chapter and Armguard more reliably, as if he gets the Chapter, he can force the Zed out of lane with pushes but he can still be all in'd due to the lack or armor, while if he gets the armor, he can still try to match Zed's shove to the point where it becomes a skill match up instead of a "hey, I'm Zed, you're a mage, I'm not a moron, so unless your jungler wins you the lane, you got no options".