Personally I think anyone with a PS+ or XBL Gold sub should be able to download any game in the PSN / XBL library that is more than 3 years old. If a game hasn't profited after 3 years then it isn't going to, and the few dollars each game earns from the PS+ / XBL subs that go with every download will add up.
Clearly the quality of games that you get to keep even when you end your subs will be lower than the quality of games that you can only play while your subs are active. I prefer the rental service, because I just got myself Tomb Raider and Bioshock Infinite for my instant game collection. 2 GOTY contenders for 2013! Oh, and Borderlands 2, LBP Karting and Brothers. That's such great quality, excpt maybe for LBP Karting.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
