Well, I would like for my games to still be playable if the store goes kaput. Impulse is dead and so are my means to play any games I had with it.

I also don't like being inconvenienced by DRM. Some stores are good in that regard.

Right now, GOG is the store for me. I can download files and use them to install games on computers without internet connection. I'm quite sure my games will be still playable if GOG died tomorrow.

Valve w. Steam: They run a flawed business which works due to the fact they got their first and have been developing their launcher the longest. The hands-off-ness should be both applauded and admonished, they go too far with it.

CDProject w. GOG: They have had time to adapt to make it a better place than steam is for both the Dev and the Consumer, but they have not done so. On the other hand, they have a platform where they can release their own games without worrying about relying on anyone outside their company, this is actually a pretty big deal in terms of minimising risk.

Epic w. Epic Store: They are doing what console manufacturers have done forever, pushing money into games is business. It's not Epic store that is to blame, it's the publishers of the game that agree to it. And I feel there is only blame to be thrown where promises have been broken. Publishers are not always the same thing as the Developers, in fact it's seldom the case, people forget that with their outrage.

Side note: While Epic may be messing up with a lot of data protection stuff, I'd give the benefit of the doubt that it's due to rushing the store out too fast.

I've been using Eneba.com lately. In all honesty, never had any problems whatsoever, they say that they get some of their games from the official providers too. The prices are good, so its a no brainer for a cheapskate like me

I don't really have a strong opinion one way or the other.  I like Steam and Valve.  I also like competition.

As others have said, there are stores and there are platforms.

Humble Bundle is a store.

Steam is a platform with a store.

Impulse was a platform with a store as well.

The Epic store is a platform with a store.

Gamers Gate is a store.

Good help. I don't think steam provides that.

I don't like buying a game, and steam telling me I can't install it because my email expired on me, and I forgot my password. Ie. Skyrim. No I don't have the CD anymore. 

When impulse, or GameStop got sold I lost master of Orion 1, and 2. That was annoying. 

I can't play my dungeons, and dragons anthology on gamers gate annoying.

Let's go back to steam. I don't like limited download speeds. 

Games I bought I can't play anymore sins of a solar empire. 

For reasons I don't use phone security to log into steam. Steam doesn't let me comment on it's forums, for this reason. This is annoying. 

steam will lock up if you don't have the internet even, in offline mode. This happened to me when I didn't have the internet. 

I would like my games secure, even when impulse, and GameStop sold. 

Now, optimally it would be nice if old games could run new machines. There were a couple of games I had to unbuy on steam for this reason. I would like to see old games that utilise new hardware. Steam has a free to play section. I would like to see a section where there is code from bankrupt companies. So some one could pick up a game that is basically legal, because it doesn't exist anymore. Or games that are so old that they don't use their trademark. If I understand this it is three years. Even if the games were other platforms this is a new section also, it could be modified for windows. 

Not having the executable on my computer, but on steam only is annoying. 

Steam let's me add other people's games to the list, but if I have to reinstall my games for some reason I can't do it from my list. This is how I lost distant world's. I would like to be able to load some one else's games into the platform. So if I forget a password I don't lose the game. 

Modding tools.

For me GOG is first choice (btw. thx for not releasing GC3 there form start , I would gladly migrate there if possible)

I never liked Steam too much but it has some advantages.

Current Epic store policy with exclusives, and creating monopoly this way, for me is unacceptable and I refuse to support this platform. I am long past age when I have to play something immediately and I can wait especially if I will get patched game at better price.

Also I would not mind getting physical copy sometimes.