Sorry to draw your attention towards this wallet, unstoppable.money, this is my first of hearing this otherwise what I uses is trustwallet for altcoin or MEW at least I can import the private keys on any wallet app and perform transactions without having any issues, although I often put it on watch list, like when I create an address on MEW i will insert it on trustwallet as only watch, to monitor transactions and check token/coin that are increasing in price.
I prefer Unstoppable because it is an open source wallet. But what I do not like about it is that it is only available on mobile device. Trust wallet is completely close source. Some developers argued that Metamask may be able to control their users keys and addresses probably because it is a web wallet and the keys are stored somewhere online. I can not recommend both wallet.