Pre-investment, you should basically balance the administrative hassle and financial burden of incorporating in the US - specifically, Delaware with the decreased friction of fundraising for a US topco.

Cons of DE:

  - US lawyers are the worst both in terms of quality and cost 
  - You may need local sub to employ you
  - If you're not in the US you may struggle to open a bank account etc in your local jurisdiction

Pros of DE:

  - Everyone knows how to invest in a DE C-Corp no matter how early stage
  - Many tax advantages for investors can be maintained (e.g. EIS for UK taxpayers)
  - Lots of nice tooling for doing company secretarial stuff (e.g. Carta)

Once you have enough cash not to worry too much about the odd moderately expensive and opaque advisory bill for something you never knew you needed, the US looks more and more attractive strategically. To the extent that some people think there shouldn't even be a debate (e.g. https://medium.com/angularventures/us-incorporation-just-do-...)

(Source: founder of UK startup with US sub, acquired by US company)