Why Akali is still strong after all these nerfs and low win rate:
She has 2 escapes in lane (3 at lv6). Her E, her W, and her R. But the main thins is her E and W.
The reason for this being, you can easily negate an enemy trade using one of these two abilities, while trading back, and then still have one off cooldown if things go badly.
Lets take Galio as an example as he is seen as sort of an akali counter.
In order for Galio to trade on Akali, he has to land either his taunt of his punch.
His ideal combo would look something like: taunt -> knockup punch -> Q -> passive punch.
Or
knockup punch -> taunt -> q -> passive punch.
If he lacks passive, he does less damage. And akali can simply E away his either taunt or knockup punch, and if Galio is not under his tower or has teammates near him, Akali can easily engage back with her E, passive proc, Q. And if Galio wants to fight you back, throw smokebomb down (W), and then get 1-2 max range Qs and passives off him. Winning the trade heavily.
If galio doesn't want to trade back, you also won the trade and now also keep your escape to deal with any ganks in the next 20 seconds.
To play Akali properly you have to learn: the max range of your Q. Its very very important to hit max range Q on enemy champions, take 1 step back and then get passive. Especially in melee match-ups.
The second most important thing is to learn the max range of your E, so that you will hit you Es to dodge stuff and reengage fights.
The third most important thing is to know what's the enemy combo that can kill or heavily damage you. So that you will attempt to avoid that every time, and if you can't avoid that (like skills on cooldown), to back down and play way more defensively.
Ie: Fizz will fuck you hard if he hits his ult on you. So, once Fizz is 6, you should avoid fighting him without your E and R ready while he has R. Even if he Qs in and Rs you, you can still live with E away, walk, and when he tries to jump on you again with E, you R away (or behind him if you're confident) and then proceed to with with your Qs, passive and W.
The 4th most important thing is to learn the range of your Q for effective use of farming and poking, as Akali's Q is quite narrow.
5Th and final thing, learning how to farm with her in the early game.
Honorable mentions: watch some streamers to see how they trade in lane in early game And how they team fight with Akali.
As you can see, especially the first 2 points are quite difficult. Akali is quite simple from a "what she can or should do" point of view, she's difficult to execute on (mainly due to having to hit abilities at max range). Meanwhile, I got troubles with learning kai'sa.