A lot of nitpickers commenting on this, but ignore them. Your basic thesis is correct: the ultimate valuation of the company matters way more than anything else. As engineer #100, say, the stock granted to you as a % of the options pool is negligible: there are effectively no differences in the ownership fraction no matter what company you choose. Whether you choose a company that grows into 50 billion vs 5 billion makes all the difference.

If you choose a company that ends up achieving a 500 million valuation as engineer #100, then your time will be wasted, massively. You will end up making no or -ve amounts of money.