I think zencash , the reason: zencash has the shielded transactions, the tls connections,  the secure nodes,  and  in the roadmap the domain fronting and the anonymous publishing system.
there is already a private message system implemented in one of the wallets,

the other coins mentioned have maybe one or two of these features , but zencash is the only one that is trying to get all, and the team is delivering.
there are a lot of updates and activities.

Personally I like the model of governance and the treasury model , for me its fair and balanced in the long term that is important.