I've heard of Coinomi but I had a great challenge getting ethereum private keys.
Somehow, I find it difficult trusting these wallet providers with my private keys. Anything could happen at any time, you know
Coinomi is one of the best multiple crytpo currency wallet and there are other with these kind is Exodus and cryptonator these wallets supports popular altcoins.If your coin is based on ERC20 then MEW will be the best option for you.If you still not satisfied security level of these wallets then buy Ledger Nano S which supports more altcoins and fully secured.