Rune choice depends on two things, that being your personal play style and who you're up against. I'm going to give you a few scenarios to help you choose what runes to go.
Scenario 1 (Unfavorable)
Nilah is an engage heavy lane bully that absolutely wrecks you in lane because of that stupid dodge ability she has. She'll normally try to take that dodge ability second just to counter you because she knows how strong your level 2 is. So, with that in mind, let's go over your options.
NO
This is NOT a good option here. Hail of Blades is good for early engagements, but why bring a rune that's good for that when you're not going to win early engagements anyway? Nilah beats you in every stage of the game, so this is essentially worthless if you want to get fed.
NO
Same deal with Electrocute. Good for early burst, but like I said, you're not winning those anyway. So there's no point in it.
MAYBE
Here's why this is a 'maybe'. Press the attack is good for burst AND longer engagements. This is a solid choice against an unfavorable matchup like this because you get the best of both worlds. You can harass her with your superior range and when you see her engage, you have a good escape, AKA your W. Don't expect to get many kills, though. This turns a lane that would normally be your death into a farming/poke lane. I mean, it's better, but it's still BORING.
YES
The best way to deal with an engage-heavy ADC that can kill you better than you can kill them is to understand how to run away from them. Engage-heavy ADCs nowadays don't have super long range, Nilah being no exception. Fleet Footwork makes kiting away from her super easy. Even if she uses her dodge, you still have a W to get away from her. Keeping your distance is the perfect way to handle this matchup.
Scenario 2 (Even)
Jhin is an immobile ADC with strong burst damage, but he's very slow with his attacks early on. His fourth shot is the deadliest part of his kit and should NEVER be taken for granted when you're laning against him. He has reliable CC and is a heavy snowballer. Take that in mind when you're choosing your runes.
MAYBE
Hail of Blades is okay here. You can jump on him, get your bomb off, get a reset, and probably get a kill level 2 while all Jhin can do is run away and shoot you. You close the distance super easily when you fight him. Your burst is much faster and much more hard-hitting.
MAYBE
This is also a strong burst pick, but I still prefer Press the Attack over it. It's not a bad pick, but why go this when Press the Attack can get you kills better? Electrocute doesn't give you attack speed. Against an even matchup like Jhin, this isn't the best rune, but I'm sure you'd still find some success with it.
YES
MAKE SURE YOU HAVE ITEMS. An early engage on Jhin can work provided your support has half a brain, but BE CAREFUL. Your attack speed is low in the early stages of the game and if you can't outdamage Jhin by the time you already slammed your middle finger on your W key you might as well kiss your early lead goodbye. But if you at least have boots or Infinity Edge, Jhin wont know what hit him by the time you stomp him into the dirt.
NO
This gives you the sustain to win in early engagements, though it's not going to be as effective as other key runes. If you run literally anything else this rune becomes obsolete because HoB and PtA just bursts him down faster than he can burst you. If you can right click your mouse then you don't need this rune. But... I guess this is also pretty good if you like giving Jhin is fourth shot poke on you. And if you do that, I must ask. Why?
Scenario 3 (Favorable)
Ashe is a lot like Jhin. Her auto attacks slow which can be annoying, and her ult is a real game-changer. But here is where it's different, her only hard CC is level 6 whereas Jhin gets his hard CC at level 2. Jhin has strong burst in long engagements while Ashe has consistent damage throughout. How would you go about this matchup rune-wise?
YES
Hail of Blades is also perfect here. Jump in, E, get the bomb off, jump out before she even knows what happened OR engage again and kill her. What's she gonna do? Slow you? You're already on top of her OR you're already out of her range? The heck is she gonna do about it?
NO
Remember, attack speed is VERY important in the early game. Don't have that? Don't win trades. Ashes typically also run Hail of Blades or Press the Attack nowadays, so this rune isn't going to do much for you. Sure, the burst is funny, but you need items in order to make it work. Why run this when you can snowball earlier with anything else?
YES
This is just electrocute but better. Although trades are longer, the extra exposed damage can make the trade favorable for you. By the time the exposed damage kicks in, your bomb will go off and deal some massive damage. However, I still think Hail of Blades is better here because it makes harassing her even easier. She has better range than you early on, so you will get harassed if you run this because you don't have as good a follow up. This will also make Ashe completely irrelevant in late game because you can just delete her instantly! (run cleanse)
MAYBE
Ashe is still a poke champion, so if you find yourself against a smelly no-good Ashe, this might help you out. The healing is nice, same with the move speed. It also gives you a bit of sustain in fights, though I find it easier to burst down an Ashe than try and get into an extended fight with her. (Run cleanse)
