Not to clone the recent swarm of "Lol how many" Threads. I was genuinely interested.
A man's collection says a lot about him.

Or a woman's, in some cases.

Mine would have to be Paper Mario.. The original one.
At the time, it was just beautifully laid out; and it's almost IMPOSSIBLE to find nothing to do in it. After killing Bowser, you can collect all the badges.
Then all of the recipes.
Then all of the star shards.
Then level up as much as possible.
Then, euh..
Then you get TTYD and it starts all over again.