Greatest Hits, Player's Choice, et cetera are all pretty much packaging variations. I don't really like think it needs a whole category. At the same time I can understand if you're someone who has over 1000 PS1 games and would like to survey what Platinum/Greatest Hits games you own.
It might be a long shot but maybe having the ability to search your own game library would be helpful. For example, all you'd have to do is type in Platinum and everything labeled that would come up. This could be useful for series that span multiple platforms. If I were to search for Madden, as in Madden Football, it could then list all the Madden games that are in my collection without having to look through each platform to find out.