I'm a fan of the party favor.
It's a super cute way to send your guests off with a token of
"thanks-for-coming-you're-so-great-and-I'm-so-glad-we're-friends-let's-party-again-soon!" (apparently my party favors are quite chatty).
She took inspiration from here
and turned some recycled frappuccino bottles into no-fuss party favors.
Anything can be a party favor, but in my experience, eatables are quick, easy and often appreciated. I also like to give ornaments, personalized items and themed items to go along with the party. But I always try to give whatever it is a personal/handmade touch.