I think the following is the bare minimum to compete with Steam at this point: 1. Store with discoverability, 2. A functional cart feature at launch 3. A wishlist with notifications for discount 4. Relatively high download speeds (500Mbps at least) 5. Friends list and activity feed 6. Achievements 7. An equivalent to steam input API 8. Regional pricing with robust payment options 9. Development/Beta build distribution as easy as steam. 10. A useful in-game overlay with at least performance metrics. optionally a web browser and notes.

All of the competition has missed either one or more of the features, making them feel like only a cash grab trying to avoid Valve's cut for providing these features.