Never heard of Epic games. What is that? I have 170 purchased games in my Steam library. I did have to get a UbiSoft account for Anno1800. Really happy about Sins2 coming out. Hope it can be on Steam, too. Seems silly to go with an unknown, unheard vendor for release of Sins2. I wonder what the thinking was behind that. I'd like to get into the Beta and pre-order; maybe Stardock can make a direct download available. Just my two cents as a suggestion.
Not sure how you have never heard of Epic Games but they are not an unknown, unheard-of vendor. They have been around since 1992, they are the developer of the Unreal engine (which probably powers a significant number of games in your games library) and are the publisher (either by original development or acquisition) of some of the most successful games in the world - most notably in recent years Fortnite. Some other notable games are:
The Unreal series
The Gears of War series
Age of Wonders
The Alan Wake Games
Anyway, they opened the Epic Game Store a couple of years ago to compete with Steam (primarily). Apparently, they have ruffled more than a few feathers by paying for exclusivity. Personally, I'm indifferent to them but have gotten a few games free from them (they give them away bi-weekly or monthly, I forget which). Sins 2 might be the first game I actually pay for from them. Regardless of how anyone feels about them, they are not a fly-by-night operation.