The proliferation of cloud computing can imply a barrier to cloud users. When deploying their complex workloads into clouds, cloud users are typically overwhelmed by too many technical choices. Moreover, underlying technologies and pricing mechanisms of clouds vary and are not transparent to them. Consequently, it is hard for cloud users to capture the monetary and performance implications of their workload deployments. This paper introduces a cloud recommendation platform, referred to as Cloud Advisor. It allows cloud users to explore various cloud configurations recommended based on user preferences such as budget, performance expectation, and energy saving for given workload. Then, it allows cloud users to compare offered price and performance with other clouds' offerings for the workload. By providing transparent comparisons, it can also support cloud provider to develop a competitive pricing strategy such as price reduction driven by energy efficiency. We have applied the proposed platform for recommendation from a real data center and some external clouds.