The safest risk reward ratio in terms of career development, networking, and financial gain is to work at a startup that is in their explosive growth stage. You will likely get shares valued at some multiple of 100k. Make sure you understand the business and feel confident they will IPO or exit.

The scaling needs, technically or culturally, of a company at this stage are unlikely to be available at a risky early startup that may never see massive growth. At a BigCo, unless you are in infra or deep in the technical stack, many of these scaling problems will have been solved for you.

In terms of networking, you will get to learn from grizzled engineers who were around in the early days, veterans from big companies who have come in to fix the shit that is wrong, and have a front seat to these cultures colliding. Not only that, you'll be surrounded by soon to be angel investors.

I spent one year working at a pre-IPO unicorn and it was highest in ROI for my career as an entrepreneur later and the IPO made me enough cash to not be sweating my rent all the time.