I did the reverse; started as a Head of Engineering at a startup, then moved into Engineering Lead/Manager roles. It was risky (we ended up getting shut down) and extremely stressful (I was involved in a dozen fires at any given time), but I learned an incredible amount.

If you can handle the risk and stress, the CTO job will likely be more rewarding.

That said, it's absolutely critical to find a mentor outside of the company to lean on. It's likely that your peers will know nothing about running engineering teams, and having an experienced voice of reason can make-or-break your experience.

+1 for "find a mentor outside of the company to lean on"

I'm an experienced manager, but this is still a hugely important point. Mentor relationships are really underrated.

>>nearly-profitable pre-Series-A SaaS startup

If the startup is loosing money, no matter how small. You would be under a titanic amounts of stress. Though I can't really judge the future potential of the startup based on the information you have provided. I'd say stay put. Use the spare energy and sanity to work on your own side projects.

This is a really good point. I agree it's a better use of energy to work on side projects while your work-life is stable, rather than injecting stress into your life.

I am a founder of $25M company.

$150B must be coming with more BS but more benefits.

If you are in a mood to relax, ofc $150B company.

If you want total control, $10M sounds more fun.

Do it, take the startup job. No downside. If it all goes tits up you will now have lead technology operations on your resume so your next corporate job will be a jump up.

"No downside"? You've been drinking the Kool-Aid, my friend.

If you have to ask this questions and are not able to provide more details the latter.

The former if you can afford it and there is potential. The latter if not.