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.
Like you, I only use Steam and Lutris. I use Steam for basically everything, even some non-steam games like Gears of War 1, and then I use Lutris for other games like BattleNet games and some Ubisoft games like Assassins Creed Valhalla.