GCP is not nearly as good from my personal experience when it comes to support and reliability of services at scale. There are certainly some instances where GCP is easier to use, or they offer certain niche services that aren't exactly the same with AWS. Additionally given how close the costs are to begin with, it would very likely depend on your workloads as to which service was cheaper.

Overall I'd say Azure is the only real competition to AWS as a product (where they are often the most willing to negotiate a big deal), but googles open source efforts potentially pose a risk.