The most common budget question has a simple frame: Google captures existing demand (people already searching), while Meta creates new demand (people discovering you).
Most e-commerce brands do well starting around 60-70% Meta / 30-40% Google, service businesses often the reverse. Then let the data reallocate: whichever channel hits your break-even ROAS first earns more budget.
Bottom line: not either/or — sequence them. Capture demand with Google, expand it with Meta.