Thanks. I think I would rather prefer non-free software as a second option.
Since I'm new to this, I would prefer to go the safe way: first Debian
10, then testing.
Be aware that although testing has less churn than unstable, that also means that when a bug does creep through, it may take a week or two to see the next release of the software, whereas unstable might see the fix come in later that same day.
It's a trade-off.