I can't see any game as a keeper to be honest but then I only have space for four! I am going to just rotate games in and out when I can find something else I would rather have. I do think with all of the new pins coming out that will put a lot of pressure on clearing out space and cash to get the new ones in. I would love to pick up an AC/DC (btw anyone in So Cal that wants to sell a premium I am out there in June/July and am interested in buying one...) but something would have to go for me to fit in in. I suspect I will not hold on to any pin for more than about 2 years because they do get old over time and I want to free up a slot for something else.
So for me there is no such thing as a keeper they are just toys, I keep them until I can find another one I would rather have!