I would only choose the startup, if they're working on something that you're personally super passionate about and if Google isn't doing work in that area. Add

I would only choose the startup, if they're working on something that you're personally super passionate about and if Google isn't doing work in that area. Additionally the startup would have to be run by people whose abilities to run the business in all of its aspects I trust 100%. If the pay is 1/3, financially the only logical option is Google.