If you don't know the answer.. then on both IOS and Android, you can check what app you spend most of your time on if you go onto screen time settings.
For me... I use YouTube the most and it's not a surprise. Whether I want to tune into a kpop comeback and stream the MV, or if I want to see what my fave youtubers are up to. My runner ups are Instagram and Tiktok for similar reasons.