Currently, Fabric supports both LevelDB and CouchDB for storing the key/value world state and history databases. At the time of writing, the beta version of OBCS only supports LevelDB as the storage option, but the potential OBCS enhancement is to use Berkeley DB (BDB), which is offered by the NoSQL DB Cloud Service.
OBCS is planning to use BDB instead of LevelDB, as Oracle says it faster in "virtually" all use cases, though I couldn't find any benchmarks just yet. The following research paper from 2012, however, points out the opposite result: http://highscalability.com/blog/2012/11/29/performance-data-for-leveldb-berkley-db-and-bangdb-for-rando.html. Nonetheless, a lot can change in over six years ...
