Try Xapo, As they are really convenient when sending bitcoins because you don't have to pay the miners fee as they already eliminated it .
But just like what the others said, Only keep a small amount of money in online wallets as they are very risky because most of them don't give private keys .
And don't try coinbase as they are very strict, every transaction is regulated they can block or even terminate your account .
Xapo is good but if we talk about a pretty good secured online wallet you can better pick the Blockchain in my eyes.
If you're looking for best secured online wallet you might visit this site :
https://bitcoin.org/en/choose-your-walletEven though xapo and coinbase are listed out there i don't recommend them like people said and many cases happened out there it's not good for storing bitcoin, just use the wallet where you can controll the private key, so whatever you do with your money even if it's illegal no one can lock it or freeze it, blockhcain is a good one though just a friendly advice.