As with any piece of software, WordPress is prone to get hacking or simply to crash for no reason.
When the worst happens, you simply need to have a backup ready to reboot your website a moment before whatever brought your website down so you can take action. And also to make sure you don't lose any traffic due to downtime.
When I was personally looking for a WP backup system for my own web properties and my customers, I narrowed my pick to the ones include the following features:
You don't want something that seems to do the job on paper and fail miserably when you need it the most.
This part is easily verifiable through a quick Google search and checking users reviews of your chosen backup solution.
It's mandatory to have a cloud storage to prevent losing your WordPress due to hardware failure. Cloud storage services like Dropbox and Google Drive are built to replicate storage so you never lose your files.
Scheduling backups help get you the closest website version before it crashes. When done manually, website owners are unlikely to commit to set the backup periodically and risk having to rebuilt their website using a much older version.
A weekly backup is recommended.
Some basic backup scripts will manually zip the website files and dump your WordPress database. The restoring process can be tedious in case you happen to change hosts or if your database is too large to be imported at once.
Thus the need for a one-click backup-and-deploy solution to avoid people all the headache related to manual backups.
When dealing with backup services (not plugins), you are likely to have a limit on how many archives you can store on their servers.
Ideally, the longer, the better. But you can settle for something at least 3 months worth long.
It needs to be a non-free but budget-friendly in case you have a lot of web properties
I usually turn to paid plugins to critical functions even if there is a free plugin counterpart. Commercial products are more likely to fix issues and bugs while the free one can be abandoned and sometimes convey malevolent intentions.
My final pick included:
Most of shared-hosting and managed hosting have a built-in backup system.
It can be a proprietary solution or an addon to their hosting managed tool (like Cpanel).
Since it's part of the system, it's usually reliable and does the job as intended in most cases.
I heavily rely on All in One WP Migration plugin. It’s the best tools to perform backups/migrations.
The process is fairly easy to do:
If your website crashes and burn and you have a working backup on hand, all you need to do is:
The free version has a 512Mb size limit (files and database) and has no Cloud Storage feature.
If you have a lightweight website and don’t need storing the backup on a cloud storage, then the free version is the way to go.
Waiving that limit will cost a one-time $69 (AiOWPM unlimited extension) if needed.
Solid performance. Never failed so far.
Or for a smarter investment, you can get Dropbox, or Google Drive, or Amazon S3 extension for $99 each (was $79 not so long ago). It removes the limit but also allows you to upload your backups on any cloud storage of your choosing.
There also have a WP CLI integration. It can be handy for sysadmins into controlling WordPress operation through commandline.
This is by far the best backup system you could get.