This paper has reviewed, compared, and contrasted major cloud storage providers, such as Amazon Web Services (AWS), Microsoft Azure, Google Cloud Platform (GCP), and Oracle Cloud Infrastructure (OCI). It critically assesses each of the services on the basis of service and implementation, strengths and challenges, and pricing. The research is done on literature that relates to academic rigor, technical documents, and market reports. This has helped to make a very critical review in the way all these CSPs' offerings address different storage requirements across sectors. A radar chart has also been provided at the end of the paper, displaying a graphical representation for the strengths of each CSP, giving a single view to researchers, developers, and enterprise decision-makers. The review also culminated in bringing out some significant trends, security issues, sustainability factors, and impacts on data sovereignty while selecting cloud storage.