Native technology tends to outlast any given proprietary technology. So I would say if it really was a black and white question, go with the web. It constantly evolves and you'll never have time to get bored ;)

But the real question is whether you like working on apps in a specific ecosystem, or if you like building for a more general case. If you like one in particular, do it!

I don't think anyone can tell you "which will be better" to become. All fields are great and preferences will differ based on individual goals and passion.

If you're trying to pick a path I'll advise you look at both fields, what it entails, the roadmap and pick one which aligns with your passion, for now, you can always circle back if it doesn't work out well.

In general, you have to test the waters to fully know what you want to focus on one path.

The 2020 Web Developer Roadmap

android-developer-roadmap

Hope this helps!