Database choice doesn't actually matter until it actually matters.

The project I want to do, is tiny and kind of niche. If it ever succeed, it will be around 1-2 million visits per month kind of website at most, I've seen some website peaking at 30m, but there is only one like that, from the data I know.

The problem you have right now is getting to that level of success. There are many many problems to solve and things to learn before you get there. Building is the only way to make progress. Building is hard work. Research is easy and not really work.

I've enjoyed MySQL the most so far

Then, why not use that? Good luck.