No matter what you choose, build stuff and be around smart people.
Unpopular but right is what you're going for.
... you can think about that for everyone you hire: will I bet the future of this company on this single hire? And that's a tough bar.
You need this sort of a tailwind to make a startup successful.
The single word that matters most I think to keep the company productive as it grows is alignment.
Growth and momentum are what a startup lives on and you always have to focus on maintaining these.