There are now many more NoSQL databases on the market than ever before. I suggest even having a look at the Gartner Magic Quadrant if you're looking for a database that will also be great for enterprise applications based on support, expandability, management, and cost.
http://www.gartner.com/technology/reprints.do?id=1-23A415Q&ct=141020&st=sb
I would like to suggest Couchbase to anyone who's not tried it yet, but not based on the version that is shown in the report (2.5.1) because it is nearly 2 revisions behind where CB Server is today, nearing release of 4.0 in 2H15.
http://www.couchbase.com/coming-in-couchbase-server-4-0
The other part about Couchbase as a vendor/product is that it is a multi-use type of DB. It can act as a pure K/V store, Document Oriented Database with multi-dimensional scaling, Memcached, cache-aside with persistence, and supports ANSI 92 compliant SQL with automatic joins, replication to DR clusters with the push of a button, and even has a mobile component built-in to the ecosystem.
If nothing else, it's worth checking out the latest benchmarks:
http://info.couchbase.com/Benchmark_MongoDB_VS_CouchbaseServer_HPW_BM.html
http://info.couchbase.com/NoSQL-Technical-Comparison-Report.html
