The issue with Dropbox or Google Drive is that they expect the files to be in their respective folder trees. If the OP doesn't care where the files reside, then these are indeed good options.
But if the location of the files is important, I recommend "Sync Folders" that is available in the Mac App store. I use it for syncing data files for a particular app that need to reside in a fixed location.
Thanks, will check out Chronosync Express and Sync Folders. I want to keep the same file structure and prefer to keep the files local only - instead of cloud (that's why I avoid using Dropbox/Google Drive)