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.
Only Steam. You can get non-steam Windows games running using Proton too. I had trouble getting Ubisoft (AC Valhalla in particular) working with Lutris and Wine, but it was super easy with Steam using the “add non-steam game” option and trying different Proton versions till one worked (might’ve had to use a GloriousEggroll version, don’t remember).