Surely PS+ Premium will grow month after month, that means bunch of classic PS1, PSP, PS2 and PS3 games.
So, my favorites would be GT1, GT2, NFS High Stakes, Metal Gear Solid, Soul Reaver, Hogs Of War, Vagrant Story, Suikoden games, Chrono games, ISS Pro, Bishi Bashi, C-12, Wipeout 2097 and 3...