I would tend to agree, knowing what zookeeper has been doing and actually using zookeeper (and etcd) I can say that the API and the primitives offered by zookee

I would tend to agree, knowing what zookeeper has been doing and actually using zookeeper (and etcd) I can say that the API and the primitives offered by zookeeper are IMHO better (although this multi-version concurrency control model is interesting) and more mature. It feels like etcd is 'still discovering itself' for lack of better words. Btw: https://issues.apache.org/jira/browse/ZOOKEEPER-2169 https://issues.apache.org/jira/browse/ZOOKEEPER-2169 (this is the equivalent of TTLs for zookeeper).