They're way more appreciative and thankful in most cases. Gifting your friends is fun and all, and it brings a great feeling, but it's almost as if you're expected to gift them and you're expecting a gift from them. Strangers, however, are usually way more appreciative and there's more value to it than 500 or 900 gralats. Last year, I was shocked just how many strangers remembered me gifting them. I'd get messages from people I've completely forgotten about in the summer time. I think the joy really comes from that feeling of doing something selfless, and as a bonus gratitude tends to follow.