uPlay and origin will never take off without opening the floodgates.
I didnt check, but GoG and Humble store probably have mor games on them.
OR I could totally be wrong and they get new 3rdpartyreleases constantly *shrug*
But really, I dont have confidence in both of these Stores. It is too much dependent on the yearly success of the companys behind them. EA can probably survive some 2 to 3 years with heavy AAA failures. but if Ubi's Open World Tower Formula burns down in the mindset of the customers, they are most likely finished. They are not diverse enough in the AAA space. They have some Indieprojects and AA PC Franchises, but if their AAA Formula fails, there is no coming back. Like 80 or 90% of their company works on these AAA games.
GoG could be in Danger when CD Project goes under. But their store is indipendent enough to survive a split of the company, as long as they dont have to burden themself with the debt of their Mothercompany.
Humble is completely indipendent. They dont have any stakes in any Gaming Developer. They must only manage their store. if a game bombs, its not heir concern, it just doesnt sell so good on their store.