First, try to be serious and don't go "remove Yasuo" "delete Duskblade" or "give me a Zoe skin where she's naked and her peepee is visible".
Here's what I'd like to change :
Adding a cap to life steal, up to 20%, and removing any "damage reduction" item that isn't a defensive item, aka
Because it makes some champions ridiculously tanky for no reason, such as 
etc
yangus Beef3 votesRemove the role of jungle https://boards.na.leagueoflegends.com/en/c/gameplay-balance/ippTiJo7-nerf-junglers
Akali is SO HOT3 votesI'm just here for the Windwall, Yasuo, and CertainlyT comments
Paintchip2 votesI would change their player behavior system to actually punish trolls, akfers and inters, NOT the victims.
5050BS2 votesRemove every thing CT lead designed.
SnugglePuggle942 votesRevert Galio rework, bring back Team Builder, and revert Runes Reforged.
Beatrice falls2 votesRevert Galio rework, bring back Team Builder, and revert Runes Reforged.
You, I like you
Fallenhawk1 votesI want see promos gone if just for Tiers but I like for both Tiers and division too.
Junkο1 votesFix the garbage matchmaking.
Fallenhawk1 votesHow would fix it . I think there not nice way to fix it . I hear it this way as in past the wait time for march was long and this was the only way to fix the long wait times.
Junkο1 votesMake it so you can only get matched against people in the same tier as you (so if you are Plat you are only playing against Plats).
I have had many games where Golds, Plats and Diamonds are in the same game, and it just ends with Diamonds stomping Golds and then solo winning the game.
Mordepool1 votesIn pro Series games. All picked champions are banned from the roster for the next game
Clockwork Mouse1 votesRemove leathery from the game. We got plenty of ways to deal with tanks without that stuff, and all people really use it for is to burst down squishy champs.
VoraciousX1 votesMake autofill not autofill me unless it's been a 5-10 minute queue, because being autofilled 30 seconds over the recommended time is ridiculous and isn't anything like what Riot said they needed autofill for.
Although I also agree with Yangus Beef. We shouldn't have a role that is designed to fuck you over 5 minutes into the game(which is really 3 minutes because ya know you're spending a decent chunk of time waiting for the game to start) where you still wanna have your 1v1 experiences.
wildfox9T1 votesif we talk about items probably 
items CD : 1.5 sec -> 0.75 sec (damage of all sheen items slightly nerfed)
less burst more DPS (those items are one of the main reasons why AP assassins and trinity bruisers oneshot people),also it feels more smooth in your rotations so i really don't mind it as someone who usually build this items line
better for the enemies that don't get insta nuked with an AA and better for the user that can use it more often/delay a bit less his combo (sometimes you are forced to wait without doing anything just for proccing the sheen with your next ability which is kinda annoying)
Emo Twink1 votesbuff armor, make turrets not be affected by armor either.
KindredAndWolf1 votesRevert Evelynn, revert Runes Reforge, make solo queue actually solo. Make Aram actually random and open all champs, remove rerolls, destroy aram only accounts. Make smurfing a bannable offense. Make all rotating games modes rotate, not just two or three and “never hexakill”. Actually give twisted tree line the attention it deserves and make it Lcs worth. The biggest one....Think of all champs equally despite popularity, play rates, or mobility... all champs get qual skin treatment and all fans of those champs are equally respected. These changes would save this game.
Hexs Fortune1 votesI would find a solution to the ever growing issue of minion block