Which bitcoin app is the best?

The best bitcoin app will depend on your needs. For example, if you want to buy and sell bitcoin, then Coinbase is a good option. If you want to store your bitcoin securely, then Blockchain is a good option. There are also many other options available, so it's important to do your research before choosing an app. Remember that it's always important to take extra precautions when dealing with cryptocurrencies, such as using strong passwords and 2-factor authentication. Also, be sure to keep your bitcoin wallet backed up in case of theft or loss.