From the standpoint of CAP theorem, Consul is AP and ZK is CP. AP and CP distributed systems have their use cases, so it's important to think them through up-front. For example, I personally consider service discovery to favor AP.

I arrived at that personal assertion by building a SD setup using our conventions + Curator + ZK. In disaster scenarios we forced into the system when testing, I was able to get ZK to basically lock up because, really, that's what it's supposed to do, guarantee consistency--if it can't guarantee consistency, then it tells you about it. Consul for us fit the bill better.

Note: This was some time ago and I do not claim to be a ZK expert; it's quite possible the root issue was me. YMMV, etc etc.