I use Steam for probably 80% of the games that I play regularly, PrismLauncher for Minecraft (modded and vanilla java), Heroic for gog and Epic, Lutris for BattleNet (as well as the original non-"Resurrected" Diablo 2), Amazon Games App (free twitch/prime gaming games), EA App (got a few free games through EA Origin several years back), Ubisoft Connect, and the launcher version of Minecraft Dungeons. I've always found the lutris interface a little clunky and unintuitive, but games and things will usually work okay if I can get them installed (which will often take me a few failed attempts before I work it out).
and finally the official itch.io app is really very good, lets you choose native linux versions of games that have 'em, as well as rather seamlessly making wine prefixes for windows versions of games.
I did also used to use EmulationStation Desktop Edition as a front-end for a few different emulators, but it seems I didn't reinstall it when I did my latest OS reinstall a few months ago, I guess I've just been playing a lot more newer games (or just running retroarch without es-de).
I guess it depends on where your games are. I have a few games on epic and gog, and for that Heroic works great. So personally, I just use that and steam. The nice thing about heroic is that it lets me select steam's installed proton versions, so I don't have to install proton multiple times.
At the end of the day though, if you can launch the games you want to play, stick with what you got.
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.
For Steam, there's not much of a question; they have a native app that gets the job done.
For Epic and Gog, Heroic makes a good launcher in general.
For Amazon games, I use the "nile" launcher.
As for EA, I've managed to install the EA App manually to a fresh 64-bit prefix; I just made sure that I run "winetricks d3dcompiler_47" in that prefix, and that DXVK is installed.
I like to use steam and heroic for all the games i bought that have drm. Bottles is my nextstop for all the non legit content,since its all sandboxed i can feel safe running content from source that arent safe.
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.
I use Steam and Heroic on my Deck, didn't tried anything else now, should I try Lutris? I've heard good things about it, but for now using Steam and Heroic for my GoG games seems enough.
Lutris is great especially if you have games that need a little tweaking that aren't a part of Steam, GoG, or Epic. If all your games are on one of those three, I'd stick with Steam/Heroic personally.
Lutris is the easiest way to get WoW up and running on Linux, for example. If it weren't for that, I probably wouldn't have Lutris on my PC.
I use Lutris, Bottles, Heroic, and Steam depending
Heroic I use for the regular free game from epic, Steam for steam games, Lutris and Bottles I pretty much use for everything else, starting on one, and if it doesn't work (as happens sometimes) trying the other
Probably not the most efficient way to do things, but it works for me
It's more convenient than Lutris for installing adhoc games, or multiple games in one bottle. Don't get me wrong, when Lutris works out of the box it's great, but oftentimes there's no recipe on Lutris for a game (eg when they're relatively unknown or new games) or the recipe is severely dated.
I find that Bottles is more like just setting up your own wine prefix and keeping it organized. I was a Lutris user for years, but switched to Bottles last year and never looked back.