The only way to truly test and compare anything is to first create a baseline for the databases in which you are creating/storing. From there, you can then test each cloud infrastructure to see how well each performs in bandwidth, storage, backup, how far back do they keep files, and this is just touching the surface. Also, another good point is how well those managing the cloud react to a disaster and can replicate the data for use.
You may consider contacting a few vendors and getting some information, both technical and cost, and go from there. Bottom line, the one who holds the purse is the one who will make the final decision, so matter how hard the techs jump up and down. So prepare your documentation completely and try to speak non-tech to the budgeting department.