Epic in the recent years grown up pretty nice, where at the beginning of its existence I didn't really thought it would hold for that long, ofc that might be due to a constant giveaways they are doing. Not that it wins just solely from doing giveaways tho, no, but the competition it might create for the steam is actually a good thing for both of the platforms. But yeah, currently steam is in the lead in terms of functionality, ofc game library, tooling, community integration (e.g. workshop) etc.