Joe Masters Emison published another study that compared the relative cost of different types of GCE and AWS machines. The main conclusions of his research in my opinion:
Machine performance in both GCE zones is the same for all types of VM
The best combination of price and performance in f1-micro (but it may have strong changes in characteristics). g1-small and n1-standard-1 are very close in price per unit of performance to f1-micro
If you need uniprocessor machines on demand, then GCE is much cheaper than AWS