It depends on what you want to achieve, and who you are.
Do a PhD if you love research, and have a good safety net e.g. middle class family who'd support you in an emergency or savings to cover several years' living costs. Have an exit plan - are you planning to go on the postdoc treadmill afterwards?
Go for the BigCo if you're unsure what to do. You'll build your CV, make good money, and learn whether it suits you well.
IMO only go for the start-up if you've got a specific opportunity in mind that you're in love with. Almost all start-ups fail, and sadly it's harder to spin those failures into something positive on a CV.
Do a PhD if you love research, and have a good safety net e.g. middle class family who'd support you in an emergency or savings to cover several years' living costs. Have an exit plan - are you planning to go on the postdoc treadmill afterwards?
Go for the BigCo if you're unsure what to do. You'll build your CV, make good money, and learn whether it suits you well.
IMO only go for the start-up if you've got a specific opportunity in mind that you're in love with. Almost all start-ups fail, and sadly it's harder to spin those failures into something positive on a CV.