In terms of security, bitcoin core. in terms of usability, multibit.
if you want to usability wallet, i prefer to use blockchain, you can use anytime and everywhere,
in phone, tablet, windows device also at apple device
web wallet is best choice for it
I wouldn't recommend blockchain wallet even this is easy to use and have high usability, but the security features is full of lack. There are some bitcoin app which you can use on android phone use anywhere everywhere, mycelium is my recommendation.