I will never ever use the Epic Store ever. It has less features than Steam did over a decade ago. Fuck all those developers/publishers that sold themselves out for what is essentially Fornite money backhanders. Any company willing to lose sales for the sake of receiving a lump sum up front deserves nothing. Now devs/pubs are beginning to stab their own backers in the back like the Shenmue 3 saga. Epic have moved into this domain so they can keep their company floated highly on the stock market. Once Fortnite money starts drying up, shares prices go down, company value plummets and shares get sold off cheap, so Epic need something to retain their high valuation so the share prices and overall value of the company doesn't decline. The Epic Store and launcher is merely an overnight knee-jerk feature designed solely for this purpose dressed up to pretend it's onside with publishers, developers and gamers. If a game is available elsewhere, I'll buy there or not at all.
Steam is the market leader - it may have a higher percentage cut per product sold but the size of the customer base and the amount of features for the sake of a $100 publication fee is quite astonishing for developers and publishers. It's a great platform for gamers with a great UI, community elements, the workshop and with sales. It is the only one to have a fixed refund policy in place. uPlay has also improved massively in recent years with most past problems non-existent. Origin is pretty bad in terms of the interface but they do have some exclusive franchises in there which are popular so if you just wanted to play those, it's worth suffering. Origin Access is also excellent value if you are interested in a handful of EA games. Unlike Steam, you're not going to be spending too much time on there not playing games.
As long as it doesn't become one launcher per major publisher, I'm happy to use a handful of established and proven ones. Bethesda already tried it, failed and have come crawling back to Steam and Epic have fucked off a few of their business associates with has seen products been removed. Ideally, I'd prefer to have my games in one place and Steam is ultimately the best across the board which is why Bethesda are back, Bungie are en route and Microsoft are joining the fray along with a few others. Epic can continue to give away as many games as they wish for free but you cannot trump experience, market presence, features and quality that other proven launchers have.