OneDrive (I use it at work): if one file fails, all files stop syncing. It sometimes tries to sync some files from teams and just never finishes. It also has very strange file name restrictions. if the file name is bad (eg whitespace at the end) it will just stop syncing anything. Still better than Google Drive as it is a standard folder. if it crashes your data is HERE.
google drive (I used that at work): on MacOS is it is utter crap as it is not a folder but a mounted thing. So it is not "there" when you login. So every application that tries to open a file on google drive just fails. Because it is not an apple FS a lot of apple apps will complain. MySQL Workbench will often fail to save and often destroy files. If not running it is not mounted and none of your files are here. you also can't copy out google files (writer, spreadsheet, etc). For whatever reason.
iCloud: some strange folder nested hundred levels deep. I only use it because of some ios stuff.
So yeah, Dropbox might be pricey but through all the years it really worked very well for me. (And I really don't care about any of the other services they have)