Be suspicious of any work that is not building product or getting customers. It's easy to get sucked into an infrastructure rewrite death spiral.
The way to have a company that executes well is you have to execute well yourself.
You're either not hiring at all or it's probably your single biggest block of time.
No matter what you choose, build stuff and be around smart people.
Most great companies in tech have been built by personal referrals for the first...at least 100 employees and often many more.
When lack of structure fails, it fails all at once. What works totally fine from 0-20 employees, is disastrous at 30.