Only from truly bitter experiences: Steam.
Let me elucidate a little in which aspect of the multi-faceted offerings of this system I have my vexations.
It is not on the fact that they sell games for download. This is done by many other companies, and the idea is excellent (even if the results are sometimes less than optimal, such as games not working). Neither their ability to be siphons for gladiatorial events on the net with their matchmaking.
It is the fact, that the games purchased (or so at least in the ones I bought through the service) are incomplete. Indeed, incomplete.
One example
A year ago, out of nostalgia I bought "Half-Life 1 - Anthology". Not the download, but a CD which includes many other classics.
I installed it.
But it was not complete. It would not run. Only 90% of a game I had purchased was on the CD.
I was demanded an internet connection to Steam.
I did not have an internet connection at home, but after much fumbling to prepare my machine and the connection itself, I succeeded.
I connected.
I downloaded the last 10% of what was supposed to be mine already.
Disconnected. Launched. Nothing again.
Was told that I need to be connected each time to play.
Found that I could play off-line if I followed some procedure.
I did. It failed.
I contacted Steam's Help services.
They started a long list of recommendations and tweaks I needed to perform on my modern machine to be able to play that 1998 game.
After four days of this exchanges, I yet had to see Mr. Freeman get to work (and probably be fired for being 96 hours late).
So my game is sitting there unplayed.
It is similar to what Boober the Pig said in his response [http://www.escapistmagazine.com/forums/jump/9.131746.2921271] up there (see number 5), on the inadequacy of patches. You want working games. From the beginning.
If they figure this is a security measure that helps prevent piracy, they are super wrong. Maybe they even help to promote it in a way, by serving buyers a useless original product.
No benefits of such a system can outweigh its shortcomings, not with me, since the shortcoming was to prevent me to play. And there is no run around that.