Neither, please. Why do I want my single player games constantly hogging data? For a few of the games available on the monthly "service" I kinda get, but there is no appeal to "buying" a stream game to me. At least with Steam, you can download the title if Valve decides to stop carrying it. Google will literally have to pay to keep hosting any titles you purchase for them not to disappear on you forever.
Terrible proposition, in my opinion.
Retro Tech Select - My Youtube channel. Covers throwback consumer electronics with a focus on "vid'ya games."
Latest Video: Top 12: Best Games on the N64 - Special Features, Episode 7