I was within 10 titles of a full NA (non LRG) Vita set and was only missing the recent releases at that time (stuff like Mary Skelter)
I sold a majority of my collection 1.5 years ago but kept everything related to three buckets: Silent Hill, Zelda and Dreamcast
I'm now within 50 titles of a full DC set and it'll be some random game to cap it off as I have all of the "heavy hitters" already.