> GOG which I have no experience with but hear its good

You heard right. They have quite a good setup: the Steam-style GOG Galaxy client is entirely optional, you can also download, install and run your games manually without hindrance.

Well done web site with lots of user reviews. They also have very cheap older games and regular freebies - they're such a nice seller that you feel like buying something more expensive (Witcher 3 at half-price was a good deal ;-)

Edit: they also have a 'connect your Steam account' feature that allows you to have some of your Steam library games added to you GOG library.

When I tried last fall, I was able to buy Total Annihilation on GoG on Windows 10 client, but unable to launch the game on Windows 10. That was rather disappointing - no messaging it would be broken before purchase, no insight into if it would ever get fixed.

Activision has historically released their games on Steam, but their last PC release, Destiny 2, and their upcoming game Black Ops 4, are both only on Battle.net (Blizzard's client). Looks like they'll be releasing their games on Battle.net from now on.

Right, there are clients/stores from some of the very big players for their products and some stores for more niche products (e.g. GoG) but I can't think of anything else on PCs with the scale and money-printing power of Steam.

I wouldn't call it good, at best it looks pretty while it is functionally lacking, especially when you compare it to Steam.

Activision is starting to move all of their big multiplayer games to Battle.net. Call of Duty: Black Ops 4 will be the first PC release of a Call of Duty game on Battle.net after it being a Steam only game for 11 years. For big publishers and tentpole titles it makes sense to completely control the platform, because people will install a custom launcher and make a new account to play a big title, and there is no reason for publishers to give away 30% of revenue to Valve. The same trend is happening in video streaming with Netflix and Netflix isn't hurting.

That said I think the Valve hating in this thread is... overblown? DOTA2 and CS:GO are some of the most played games period outside of Fortnite, LOL and PUBG. HN has been complaining about Valve not releasing a new game for years but why release a new game when you have multiple, popular, heavily played titles? All the complaints seem strange coming from a site where many of the users work for SaaS companies that don't follow a business model that requires releasing an entirely new product every year or two.