Labymod can be modified to where it’s useable for competitive gameplay with mods downloaded using forge, but Badlion Client already has them built into the client so it’s much less of a hassle than trying to find all the right mods to download to make Labymod anywhere near comparable. The only mods I can see a problem with is mini-map which could of course be disabled if Mineplex would partner with the Badlion Client.
It's much easier to download than forge+ all the 20+ mods you'd need to have the same client.
Firstly I'd like to discuss Badlion Client itself.
