I got hacked few months ago. I used the EVERNOTE online notepad to keep a backup of my wallet's phrase key. Few days later, every transaction i send to my wallet get's directly sent out to some other wallet address. There's no way to recover that account. I have tried many way to recover it and done many things.
I was trying to find the main reason and how they hacked my wallet.
so i saved another wallet's phrase key in Evernote again and waited.
to my surprise that one got hacked too.
Here's the wallet address for you to check out : 0x8E456599dB2429cFf0AC8f9d5b5aA29E7C921642 &  0xaE8e5e5263bc23D84794FbDeb6e1ea00D106b7cA     
Scan it on ether scan polygon scan and other to see how it's happening.

So from my experience, never save your secret key in online storage. make multiple offline hardware copy and save them in different places.

One way i was able to avoid getting hacked while saving it in online was to scatter the word and add some random words which you will remember wasn't there. Or you can create a sequence of numbers or a pattern and scatter them in that order so you can re assemble them using that patter.

But offline is 90% recommended.