A client itself won't instantly make you better at PvP, but certain clients help boost smaller interactions. Clients such as Cosmic, Badlion, and LabyMod are the most commonly used, but all are very different from each other in their own ways. Badlion Client is the most popular in terms of competitive modes, and lets you customize your UI a lot, boosts frames compared to a vanilla running game, and looks really nice. You can set waypoints, use schematics, and has loads of features to help customize the look of your game. Cosmic Client runs very similarly, but has less features. It helps boost frames the most, and is better for Factions specifically, as it's designed for Factions servers. LabyMod is definitely the most customizable, but people prefer Badlion Client as it's better for PvP and has more features. I use LabyMod because I play on a Macbook, but it has features like Damage Indicators, Minimap, and loads of fun addons that you can mess around with. If I were you, I would go with Badlion Client or LabyMod. Both have a lot of features to boost FPS and the ability to customize everything.
Before you go crazy on Badlion Client, Just so you know it was hacked some time ago so just because you see someone using it does not mean they are legit, 90% probably are but the client can now be toggled on and off, and another mod you might want to look at is 5 zig its similar to Labymod.
I used to have vape and never gotten me banned once lmao I've also been ss'ed so many times on so many different servers also you can use it on a lot of client sided anticheats like cosmic client, ocmc, and badlion client and more
and yes you can cheat on badlion client, it's hilarious how people try to use badlion client as a way to prove they are legit.