I wouldn't mind buying if they were cheaper, and you could dl again should you have deleted and want a replay. Which is normal.
Not very used to the concept of renting games, but I wouldn't rent for half price of owning. Buying a physical copy I can take my time, play however long I want and usually still manage to sell it half price. So renting should be lower for me to consider.
I don't intend on upgrading my 20GB to anything larger though, but that's because I rarely play more than one game at a time.