I have three different sizes and I use all of them. I'm usually home during the day and since I have a dog I'm reluctant to set one and go off for the day but I still find them useful.
I made apple butter and pumpkin butter in the crockpot. I froze the jars and will use them as Christmas gifts. There are also crockpot recipes for various candies that I've done in the past as gifts.
I make chicken in the crockpot and then shred it for various things like homemade pizza, chicken salad, tacos, etc. I do freeze it but you don't have to have a huge freezer for some of this stuff.
Since I live alone I'm not always in the mood to make dinner for just myself so having a few homemade freezer items is very handy.
If I don't want to eat something forever, I'll use the 1 quart size and that will usually make one meal for right away with leftovers for the next day.