I will share the suggestion shared by "Jack ma", the founder of alibaba group. He said, To become an entrepreneur "One should work for small companies, generally in big companies, you are part of the big machine, but in small companies, you do most of the work your self and learn it". So, it depends on what you want to be, if you plan to put your self in stable career without much of risk involved - go ahead with big…
I think this is only true when the startup is really small, say, 5-20 people. I was once part of a startup that had ~100 developers and I hardly learned about its inner workings, was rarely part of any decision-making on business or customer-facing use cases etc.