About current leaders:
Monero is good, but it's not completely anonymous, you'll need to get hands dirty to achieve high-level anonymity. Also, as a top coin, it may be overvalued currently.
ZCash - sorry, but it's a shit, with their 20% founders rewards. I used to like ZClassic, but the last announcements about BitcoinPrivate disappointed me, now I think this it's just another money grabber.
Verge may be good, but there is no doubt that it's currently overvalued, especially after McAfee's "coin of a day".

I choose DeepOnion for myself. It's young (so likely underrated currently), It's developing fast and doing much better than other new coins in this category, also DeepOnion has much more features, so it's not just a currency.