The answer is, whatever channel you find the most fun to use. Maybe it's TikTok...where to people talk to you already? Simply saying, "If you like this check out my YouTube channel" isn't enough. You have to proactively engage people on the platform that you choose.
Some questions to ask yourself.
1. What's my target demo?
2. What platform do they go to
3. Do I want to be on the platform, a LOT.
4. How long do I spend on the platform before I reassess
5. Should I focus on YouTube and just build my audience there
6. Should I work on my production, concepts and content?
If you go through these 6 questions. You'll have a better sense for what you are willing to do.
The bottom line is this, we can all suggest an app to focus on....but we won't have the answer for you.
It's all work.