I like them both. We don't know enough about the universe to say definitively whether zodiac signs are real or just fantasy. People see themselves in them and like gamifying their life, à la a video game, so they take on their zodiac like a Hogwarts house and proudly display it to the world. You might read that and think I'm being mean, but I'm not. I don't see anything wrong with that.
It doesn't mean that they're stupid, it's just a bit of fun and an attempt to form connections with others.
In regard to MBTI, it's just a baseline for your own personality. Some or much of it might be accurate to you, and it might change again the next day, but I believe there will always be a kernel of truth in there somewhere. Statistically speaking, there are just so many questions that you're bound to relate to certain answers and outcomes. It's just a foundation to build off of.