No communities, no guides, no VR , no game streaming, annoying download manager, annoying friends tab, no steam deck, no game collections AFAIK. When Fall Guys came out for free I gave the Epic launcher a real chance and it was incredibly limited in it functionality and frustrating to use compared to Steam.
Steam is shaping up to be your all in one library for anything games be it PC, VR or portable. The Switch, Quest, Playstation, Xbox and Epic launcher all offer a piece of that experience but having a unified platform that syncs your saves and doesn’t nickel and dime you for features and accessories is why Steam is more popular.
I haven’t been using Epic enough to really compare with Steam sales but stuff gets really cheap on steam really fast. I would also gladly buy my games for money on Steam just to be able to play them easily on my Steam Deck. Also Epic is only doing the free games because they have unreal and Fortnite money, there’s no telling when the free games will stop.