Monero and ZCash are two of the most well-known cryptocurrencies supporting strong features for private transactions. Some interesting posts on ZCash and Monero recently:
Before reading the posts above, I did not realize that neither Monero nor ZCash had mobile or hardware wallet support. (Monero does seem to have a workaround through a mobile wallet that can be used on Chrome.) Obviously, that will hamper their adoption in the long term. On Monero’s end, the reason for this is unclear. On ZCash’s end, it seems that the heavy math involved in using Zksnarks for private transactions was preventing mobile and hardware wallet support. Hopefully the development discussed in the first post will make it more likely to emerge in the near future.