NoSQL Database Comparison Chart (only one you need)
Following is a great resource for any one considering different choices for their "NoSQL" style frame work. As always, "one-size-fits-all" approach does *not* work for NoSQL frameworks. Just as a side note that MongoDB, Cassandra and CouchDB are the top three skills sought out on indeed.com (popular aggregator of job boards) of all the databases in the table below. Having a large pool of talent is always a good thing for your technology choice.