Look, it's something few people want to admit, but it needs to be said:
Divers, juggernauts, and assassins will never be both fair and good at the same time, at least not in their current state.
Why is this? Well, it's because of the inherent designs of each class.
Assassins are designed to burst squishies and get away, right? Same as mages, but more damage and lower CC, and melee range, versus long range?
Well, the thing is: In melee range, there's nothing to miss. Unless it's something based in timing, like Riven or Camille, there's just nothing to screw up once you're there. The fact that you have skill shots is irrelevant, because you're point-blank.
This problem means that there's very little someone can do to outplay the assassin, except for just staying the fuck away (which can only be done so much, given how fast many assassins are, even without something like Youmuu's to speed them up more). This means that either the squishy (ADC, enchanter, or mage) is killed with no way to fight back, or that something has to be done for them to be able to ignore the burst.
What does this lead to? Assassins are either going to do unavoidable and uncounterable damage (which lead to the ADC in 2k17 meme - ADCs just couldn't last against assassins), or they'll be basically useless (What most of them are now).
Is there any balanced assassin? Possibly. Out of all of them, I'd say Evelynn is pretty balanced right now, because her engage requires her to land a skillshot (Her Q) after a noticeable delay (Her W). Her damage goes way too high against squishies late-game (lmao who needs to cook your W when Q>E>Q2 kills them?), but there's noticeable counterplay to her for the rest of the game.
Juggernauts are designed as the mirror of ADCs. They're DPS, but melee instead of ranged, tanky instead of squishy, and their weakness is staying away from them instead of getting to them.
However, as they stand? With that weakness being staying away from them? They'll never feel balanced to fight as any melee champion - They're designed to win melee fights. Again, we run into the same problem we find with assassins - melee range has nothing to dodge. It's entirely on them to screw up at that point. This leads to two outcomes: Either you can kite them, and they lose, or they can't be kited by you, and you die.
Is there any balanced juggernaut? Honestly? I have no idea. Darius is close, but he's not there. He's too impossible to fight as a squishy melee, but with a few tweaks, he would be good.
Divers are basically a mix between the two. They're a bit of everything. They have some burst, some durability, some CC, some DPS... And that's a problem. Generalists aren't good in a 5v5 game where at least 4/5 roles are already taken up by specialists. They have nothing unique. This means they'll either Crowd out specialists by doing what they do and more, or they'll be useless.
Is there any balanced diver? Honestly? No. Because none actually manage to be non-generalists.
Is any of this fixable? I have no idea. Divers would need to be reworked entirely. Juggernauts need to be more like Darius. Assassins need to be more like Eve.
Just my thoughts, though.
