Oh man, that's a tough call! What was the main thing that pushed you toward the one you ended up picking? Like, were you more excited about that project in the moment, or was it more about what you thought would be popular at the swap?
Isn't it funny how we always know in our gut but talk ourselves out of it? I had this same exact problem last year picking what to bring to a craft fair. @hunt.jana is right though, going with your gut is key. For me, I picked the project that made me happiest to work on, not the one I thought would sell. Ended up getting more people interested in it than I expected, so it worked out. You just can't fake being passionate about something, people pick up on that.
Watched my friend stress over a similar choice for a comic con. She picked the art zine and instantly regretted not sharing her writing. Sometimes you just have to go with your gut on creative stuff.