Coming from the hosting world and watching the first incarnations of the "cloud", you will find fewer cynics than me
There is always a single point of failure, platforms do have catastrophic outages and human beings misconfigure databases or security and screw things up.
But the "cloud" has moved on a long way in the last 20 years and matured. Pretty much everything data wise utilises the cloud in some shape or form, from Netflix to Facebook and everything in between.
For yourself, it depends what software you are using. Storage wise, cloud space is peanuts, so it's down to a provider. If you use Microsoft Office, then by default you should have access to "One Drive" which is Microsoft's cloud solution and will give you the saving and editing ability you need. You can also collaborate with other people.
One I've used for years and I utilise for backups and transferring files to remote team members is dropbox. Fast reliable, plenty of options to suit any budget, think they have a free option as well.
If you have a Google account (who doesn't!) then you can use Googles version, which is Google drive, and you can edit docs, collaborate, share, save in the cloud etc. Then there are a multitude of third parties offering simial services for varying costs and quality.
The advantage of these services is you can synch and access docs across multiple devices. Security-wise, always go with 2 factor authentication, all services utilise this these days and use individual complex passwords, never share between accounts.
Final one, I'm still conscious of the type of data I store online. There are data breaches all the time, so for me, I won't store any sensitive information, financial or customer sensitive via public cloud services. But that's down to yourself, level of risk and type of data you are capturing.
Hope that helps.