Good titles that are/were not on 360 and PC? Getting for MGS legacy.

Long story short, I'm thinking about getting a used ps3 in order to play the Metal Gear Legacy collection. However, I am curious as to what else I can look forward to playing? I've got a pc gaming rig so big titles like Skyrim or CoD I have access to. Also, how is the indie or download library of ps2/ps1 titles, if it's possible to download old titles? If so any recommendations?

Thanks!

tldr: What good on ps3 not also on pc and is there a catalog of classic ps1/2 games you can download, if so what are recommendations?