TLauncher - There are not so many good Minecraft launchers nowadays, and yet they exist – TLauncher being one of them.
MultiMC - Overview: MultiMC is a free, open source launcher for Minecraft, managed by Forkk13and peterixxx...
MC-Launcher - Custom Minecraft Launchers
GDLauncher - GDLauncher is a custom Minecraft launcher with simplicity and power in mind. It allows users to create custom instances (also with forge), download curse modpacks and mods and more!
Prism Launcher - A custom launcher for Minecraft that allows you to easily manage multiple installations of Minecraft at once. It is a MultiMC fork.
PolyMC - Fork of MultiMC with additional features like mod downloading and supporting other package formats like flatpak or appimage