Honestly, Sony has proven to be the best company for indie developers or digital distributed game developers to work with. MS is very limiting in what they will deal with in terms of really supporting good games and how flexible XBL can be, Nintendo has a lot of bottlenecks (and awful interface) on the Wii Shop Channel, but Sony is willing to promote good indie games and let them do what they want on the PS3. It's very, very different from how Apple treats downloadable games on iOS platforms.
That said, it's different when you're talking about games that are full-sized retail products being downloaded. Apple doesn't have in-store purchaseable software for the iOS and is, frankly, aiming for quantity over quality, so its a very difficult comparison to make. The PS3 and PSP currently have Minis, which are iOS-style small/quick/cheap games, but their focus is still on big titles like Metal Gear Solid and Monster Hunter.







