If you want to talk about real champ disparity: Heimerdinger.

Not so much his W, E or R...but his Q. His turrets.

Here are Heimer's turret stats:

150-575 HP (+5-40% AP) per level 12 / 18 / 23 / 29 / 34 (+ 15% AP) shot damage 40 / 60 / 80 / 105 / 130 (+ 55% AP) laser damage 1.75 AS 525 Range 10-80 Armor 25-65 MR 3 unit cap

Now compare Zyra's plants:

4-6 "Hits" per W level 29-114 (+15% AP) damage for both plants 0.6 AS 400 Range for Thornspitter, Melee range for Vine Unlimited cap but realistically around 2-5 are your usual

And Malzahar's voidlings.

3 HP 30 / 35 / 40 / 45 / 50 (+ 40% bonus AD) + 10 / 15 / 20 / 25 / 30 (+ 20% AP) bonus magic damage 0.83 AS Melee range 30 Armor 50 MR

So here's the real question: Why does Heimerdinger, whose kit relies more on setting up turrets, have statistically the most frail units?

Heimerdinger's turrets late-game get absolutely demolished by merely tapping them. God forbid it's a long-range ADC like Caitlyn who can ping them out of existance in one auto-attack or a hardcore AoE mage like Viktor. more importantly, they don't even bring that much more damage to a fight. They'll be demolished before any shots get off because of it.

Meanwhile, Zyra and Malzahar can dump their units out freely and get free hits in. Which is partially why they're so strong and MF is such a viable counter; she can bypass their HP ticks.

Tweak Heimer's turrets. Give his turrets the pip-system the others have or tweak his turrets to actually have strong stats late game. Because these things are pathetic comparative to champions who have the minions as a gimmick.

(PS: I didn't include Yorick because his ghouls are AD-based and are made to be quickly killed.)