There are many wallets myetherwallet is the safest as i think. Because they give you full control over your account they dont store your private keys . there are also some othere wallets like coinbase ,mycelium etc .coinbase doesnt provide you private kesy of your account but it is safe till now .but when the price is going up and down you ll face a lot of problems
only hardware wallet is the safest option (Ledger the best, as option KeepKey and Trezor)
After the best option is iOS application for bitcoins breadwallet. iOS itself is pretty good with security and breadwallet is the best app for now for keeping bitcoins
None of online wallets are safe do not hold your bitcoins there, you are at risk to lose them all