For me the best privacy coin is still monero. monero has been a popular alternative cryptocurrency among enthusiasts who favor anonymity over privacy and sits in the background serving its purpose as a useful and private digital currency.
At some point Proof of Stake will be refined enough to provide a security to a network comparable to that of PoW, and then it will be practically superior to that. The fact that it hasn't happened yet is because it is a tougher / more complex problem than securing a network with PoW, and there is also the historical reason of Bitcoin, the first one being based on PoW. Plus there is a hype about it. Interestingly enough, people get emotional sometimes about this PoS vs PoW debate. I think this stems from the BTC maximalism...
Otherwise I really love the idea of Monero, even though I don't hold any of it at the moment for the above reason.