Is there an Android wallet, that allows for quick and easy BTC/LTC/ETH transfers (like to pay a merchant at point of sale); but also has a menu to let you top-up your balance and buy more crypto?
Coinbase is the best ever wallet with exchange you can buy BTC,BCH,LTC and ETH in coinbase exchange but it is not available in all the countries so check the official webiste of coinbase to know about that features are available or not in your country.
Blockchain.info wallet also comes with builtin exchange where you can buy bitcoin and ETH only but I never tested this feature yet.