Actually, Jafryn's list looks about right for what he listed them for.

I'm not talking about the clearly overpowered release Vayne, I'm talking about the Vayne from around a year ago. And Nautilus wasn't balanced on release (no champions are) but he was overnerfed. Riven stopped seeing any real competitive play after her last round of nerfs. Riot has openly acknowledged that Akali was only nerfed because she stomped low skill players.

I think she was picked four times throughout the entire tournament.
She was picked twice in the finals, by (probably) the best Vayne player in the world. He did well with her in one game. Which isn't that surprising considering Bebe showed he could crush Woong with any ADC matchup, including Caitlyn.

Vayne fell from an all-around solid ADC who saw a lot of play to an extremely situational niche pick.

right click carries shouldn't have their abilities be scalable by attack damage.

it doesn't make sense since you ap doesn't make annie right click harder.

Who actually defends Rengar? Rengar with zero damage items can use one empowered Q combo at level 6 and deal more damage than all 3 charges of Akali's R, Q, and E in a third of the time while she has Hextech Revolver.

For one thing, Akali was heavily overnerfed.

Rengar is a early game heavy burst assassin. Akali is a late game champion.

Rengar is basically a melee AD LeBlanc. The people who want yet more nerfs for Rengar are saying the exact same things I heard people saying a year ago when they were trying to get LeBlanc nerfed.

Rengar is pretty strong but most of that was just riot trying to fix bugs that would inevitably give him more damage while also giving him more damage, it's going to take a bit to fix. Actual ratio + base stats wise though I think he is weaker than he was on release.

You can think that, but Rengar's win rate and play rate rose something like 15% after the bug fixes. Riot frequently uses similar stats (albeit, their own collected stats) about win and play rate to determine which champs need nerfs/buffs/QoL fixes.

It's actually quite simple. Nerf the damage of his Q. I can live with the passive; it's the insane damage he can do after using the passive that makes him horrendously gamebreaking. A single Q combo often outdamages entire spell kits of other champs almost in an instant.

Really...? Akali is great early-mid game, lethal when she hits 6 but effectively worthless unless she snowballs, as opposed to Rengar who has greater escape and gank capabilities without needing to rely on items for his absurd Q damage, and at virtually any level.

I'm not saying he isn't good, the burst damage from q + heal and resistances given from the w are definitely strong and should be toned back a bit. Just that his actual damage on the buffs was hardly touched but the bug fixes and general QoL changes are what helped him be good, even though damage wise he was already good on release but everyone played ap rengar instead.

Akali is weak without items, because she's a mid to late game champion. But I could be wrong on her. I haven't really seen her played since she got nerfed.

Rengar is stronger without items, because he's an early game champion. He falls off really hard if he doesn't get a large gold advantage from his early game. Rengar's escape and gank capabilities are both tied to his ultimate, he can only do one or the other.