Seems like every week over on GamingOnLinux there’s an announcement of a new launcher.
Personally I only use Steam & Lutris. Lutris for my gog games and BattleNet, Steam for everything else.
I don’t know of a good reason to use Heroic, or any of the other new ones over Lutris / Steam, but maybe I’m missing out.
Personally I like to have as few launchers as possible for my games, lol. I have Steam and Lutris right now, but I’ll probably install Heroic at some point for Epic Games content. I prefer the UI of Heroic to Lutris for GoG/Epic games, plus it’s stupidly easy to claim the free Epic game from Heroic. I haven’t tried it from Lutris to compare.
As I said in another comment, I probably would just run Steam/Heroic if it wasn’t for World of Warcraft. Lutris is the easiest way to get it up and running on Linux.