Chocolate chip wins on raw volume, and it isn't close. It's the default add-on for households ordering bread, especially with kids in the mix.
Snickerdoodle wins on repeat rate. People who order it once order it again at a noticeably higher clip.
The difference is in what each cookie does. Chocolate chip is familiar and safe. Snickerdoodle — cream of tartar tang, cinnamon sugar crust, soft center — is the one people didn't know they missed.
Both bake in small weekly batches and both hit their caps some weeks. Cookies are the second-fastest item to sell out after cinnamon rolls.
Undecided? Order both. It's a cookie, not a mortgage.