Both albums got a lot of spin from 15/16 year old me, but I'll go with Birds. Though I didn't care too much for Carti until Die Lit came out and I listened to Self-Titled after the fact.
Birds just has more layered production, a lot of great features, and the vocal effects Travis Scott uses were more appealing to me.
Carti's style of "rapping" used to leave me underwhelmed, especially with how fire the beats were. Not saying Travis Scott is a spitter lol, but he gave you more than sparse mumblings and adlibs.
Ironically, I listen to Carti way more than I listen to Travis Scott now lol