Both are fun to me, but I will admit, I like the bigger ones better. Though the little ones are great for eating small portions, especially if you don't want to eat a lot and get sick, but still like bigger. >.>
Large candy bars are individually more fun, but since the fun sized ones tend to come in groups, their collective fun can overtake the large bar should their group get large enough. If it's just one of each, then the large one wins every time.
I like the sharing bags cause they're typically a little bigger than king size bags, even thou I have no intention of sharing.
Not gonna totally knock on the mini ones as much as I have a major sweet tooth, they're good for when I need just a little bit of sugar and can easily tuck them in my lunch box.
Large candy bars are individually more fun, but since the fun sized ones tend to come in groups, their collective fun can overtake the large bar should their group get large enough. If it's just one of each, then the large one wins every time.