I suppose I'm a "young person". I prefer Snapchat because you can be yourself. It's private by default. There's no pressure to post amazing things. I often just post almost-spam crap that my friends and I find amusing - like doodles, bad selfies, a picture of a cool carpet. It's easier to avoid showing off - which I really don't want to seem like I am. The filters and drawing features make it easy to add info to a picture (location, temperature, pointing out things, etc).

I avoid Facebook for many reasons. You have to be careful about who your posts are seen by. It's public by default. I have colleagues, family, and people I've met just once or twice on there. Any posts I make need to be inoffensive and anodyne. Scrolling down a Facebook feed fills me with FOMO, jealousy, rage, or other negative emotions. It's obvious they don't actually want to improve the core product. I feel used.