I compared launch price across Steam and Epic for a few games a while ago both cost the same.

Why would I choose Epic and loose

- Linux support - social features - the workshop - (mostly) having a single launcher

They also pulled a few games off Steam just before launch after they'd already been advertised there.

And adds to the glut of storefronts and launchers PC gamers need to have installed. I don't think there's any issue with providing a competitor to steam, but in practice it's not 'oh, I can switch to epic game store', it's now 'because epic has paid these developers some money, I need to go to them if I want that game'. This, in combination with a lack of feature parity with steam, is why people resented epic. If they hadn't basically pulled several games off of steam when they launched I think they would have caught a lot less flak from the community.

(console exclusives, are of course this but much worse, but at least there's some decent amount of effort involved in a port which means it's not just exclusivity deals that make a game only available on one console, as opposed to an almost entirely artificial limitation)

What do you mean by third party clients? GOG Galaxy? Steam?