I'm an analysis/numbers guy - I'd make a chart with all factors that are important to you (art, how much you play it, how much your friends/family like it, how hard it is to sell, how much $ you will likely get, etc.) This should knock out 2-3 you most likely want to keep. Then decide between the other 2-3. Don't sweat the decision that much - you can always buy it back later (there is a good thread on here - "which game did you own more than once") - although if you have a really nice version of an older game it may be harder to obtain the same condition. Good luck!