I used GCP before and liked it better than AWS. The current startup I work for has a prior business relationship with AWS, and every month, it gets harder to move off to GCP. AWS gave a generous credit to the type of startup we have, and with the relationship-building from the solutions architect and account manager, this probably won't go away.
There are a lot of technical refinements in GCP that makes life a lot easier than AWS, but nothing strategically compelling enough for the cost (in cash, developer time, and burning relationships) to jump ship. So I make-do with the not-as-great technology. They are pain-points but not deal-breakers.
I think if our startup were doing AI/ML, or even heavy data processing as our core technology, there's probably enough compelling reasons to invest in a move to GCP. But it isn't.
If I were greenfielding a new launch at a new startup, I'd push for GCP.
I have never worked for Google or Amazon.