This is a wildly nontrivial question. Volumes are written about building data warehouses, and there's a lot to consider. In a large complicated environment, you could spend weeks doing comparisons (some people spend years, but that seems extreme); and some of the decisions are worth weighing.
The first question is what capability are you looking for -- why are you sure one of these vendors is correct, and have you truly explored your options? If you want a place to capture and gather lots of near-real-time sensor data, then Hadoop might be good, if you want a more traditional Kimball or Inmon style warehouse for a small or mid size amount of data, then Microsoft, Oracle, Teradata, IBM, MySQL, and others have decades of experience that is, in fact, useful. But that's just a single-source vendor, and your question is focused on database vendors. Asking what "capability" you need includes ETL, Reporting, Meta Data, Master Data, Data Quality, User Interaction, Training, Methodology... if you're going to in-house all of that, or spread those things to multiple vendors then your answers will be different.
All of those lead to follow-on questions. Where does cost play a role? Watch your up front costs vs long-term TCO. Do you have a development team with any expertise that may make it easier to in-house decisions and developments for one platform over another? Is your corporate buy-in strong so you can weather people second-guessing your decision? There are technical issues, personnel issues, cost issues...
The first ANSWER is really that any vendor will work, and every vendor will have different headaches. Older vendors have very specific ways of doing things, but that can make developers less expensive and more uniformly capable (although you'll always find extremes). Asking several Oracle DBAs to question each other and report back on each other's competencies is rather easy. With newer capabilities like Amazon, Google, and other cloud-big-data vendors, the landscape is newer, people are using different approaches (each of which may be valid), and it's not clear which are going to survive long enough to have the richest eco systems. But again, these systems came into being for a reason -- Hadoop and NoSQL databases can perform better and more cheaply than older databases in raw throughput, or unstructured data, or other areas but they sacrifice different things -- ACID compliance, strong typing or data models, or what have you.
Some of it just depends on taste. Some people avoid a single provider "lock-in" and pick and choose different ETL tools (see Informatica), Reporting Tools (Cognos, Microstrategy, Tableau, Jasper, Pentaho), and other tools (Talend DQ/MDM comes to mind... there are many), while some people prefer single vendors due to massive integration (particularly Microsoft if you're a Windows farm). If you're Gmail based, then Google's apps have good integration; if you have an Oracle ERP then several tools speak nice to it.
I'm generalizing a lot of examples that don't always apply, to keep things shortish, but the bottom line is that every option has strengths and weaknesses. I wish it were easier.