The most of the privacy coins are undervalued right now.
The best opportunity is to find a privacy-related project with a low total supply (less than 100M), that way the price will be increasing much faster.
I recently found a hidden GEM called Ethereum Meta, it is related to anonymity and untraceable transaction. They have a very interesting project to build the Anonymous E-Market Place.
They are already trading on some exchanges, you can check their website: https://ethermeta.com/
Or even better go through their Bitcointalk thread: https://bitcointalksearch.org/topic/future-of-privacy-ethereum-meta-foundation-of-anonymous-e-marketplace-2659058