Google Cloud Storage vs. Amazon S3
David Byttow

Since this was written in 2013, a deeper comparison I found in 2016 from someone that benchmarks AWS, Azure and Google Cloud storage:

You always need to run your own experiments - but as someone on reddit commentedNot for network throughput on GCP. It consistently beats out all of the competition by a such huge margin that if you’re writing an App that’s latency/bandwidth sensitive on the network side just ignore the competition.