I recently started using OneDrive more. Mostly because our company made the switch internally to OneDrive for business and I got that sweet, sweet 1TB of storage.
Personally, at home anyways, I am a google drive user. One of the great features about Drives sync client is the ability to sync any folder of your choosing to their cloud.
By default with OneDrive it only syncs what is in the OneDrive folder. This path to the OneDrive folder can be changed but by default it is located at C:\Users\%USERNAME\OneDrive-$Businessname
Now there is no true way to sync custom folders but there is a work around, a way to trick OneDrive by using Junction Links. A Junction Link appears as the full folder structure to the folder it lives inside but is actually a link to another location. In the screenshot below you can see I have linked my whole "My Documents" folder to OneDrive (click for larger image)
To create this junction link is a simple set of CMD commands. Remember to run as admin. You want to run the command as follows
mkdir /j "C:\Users\(your user profile)\OneDrive - Business\Name of junction folder" "C:\source folder path"
The Junction Link does not have to have the same name as the source folder. In the screen shot below you can see the command I ran to place "My Documents" inside of OneDrive.
I hope this helps you to unlock some of the potential of OneDrive. Please note that as far as I can tell this is not a supported solution to what appears to be a blatant lack of a modern feature, proceed with caution, please consult your physician before using, do not operate while impaired, additional taxes and fees may apply, etc...etc...