We'll never link advertisements to Furbooru, you can be sure of that
-most of the existing aliases for tagging purposes
-ID retention from derpi (no conflicting IDs when you want to search something + doesn't fuck with dupe saves)
-Best DNP policy (though it could at least have a delayed upload for art packs, so the artists can make at least some money), which makes it the purest archive site.
Downside is the actual user traffic. Came out the gate the latest, so it's got a fraction of the userbase that the others have. Well, that and an unknown number of existing derpi IDs missing/errored.