The best wallet for long term cold storage is a paper wallet or something like CryptoSteel. For a hot wallet I would use a hardware wallet like Trezor. Trezor should have an updated model out by the summer. Not that there is anything wrong with the current version. If you have to use a software wallet I would get Electrum . Most Bitcoins are lost due to user error or lack of knowledge about their method of storage. Practice with what ever wallet you choose using a few mBTC's sending and receiving Bitcoins until you are comfortable with it. Next I would put a few mBTC in my wallet of choice and delete and recover the wallet until you are comfortable with that also.
https://cryptosteel.com/
https://trezor.io/
https://electrum.org/#home