So, I've looked at several reference managers, but either they're not clear in describing their functionalities or they don't have what I'm looking for. I'm currently using Mendeley and have looked at several others (including citavi, bookends, and zotero among others).
What I want is the following: I want to be able to add keywords/tags to each reference (available in most reference managers), then I want to have the files organized in certain folders based on specific tags. Last but not least, I would like the main folder to be in an external cloud service (preferably OneDrive), and if I add new references to that folder I want them to be automatically added to my library. Also compatible with either LaTeX or Word (But this is the case for most).
Extra benefits for me are, browser plugin for easy adding such as Mendeley, easy accessibility through an Android device (phone), plugin or easy way for quick in-text citing in word (or in latex), and preferably free/open source or one time payment.
I'm using Windows 7 and 10 as my operating systems so the reference managers should be compatible with that, I'm willing to pay up to around 100-150€ if it does everything I need and suffices with a one time payment.
To give a bit of an explanation where mendeley falls short, I can set a watch folder in Mendeley, like my onedrive folder where I save references (PDFs). This means it will automatically add them to my references in Mendeley, which is great (I need that). However I can not use that folder as the synchronization/download folder for Mendeley, because if I do it will generate many duplicates. Now the problem is if I add references through the browser plugin, the papers will then be stored in the download folder for Mendeley and not to my folder in Onedrive.
This has a few issues/problems, it means that I have every file twice on my computers, once in my onedrive and once in the mendeley download folder; it also means that when I add a reference through the plugin it doesn't sync to my onedrive folder.
Now another section where mendeley fails is the limited capability of it's function of sorting files in sub-folders. I want to be able to sort files based on important/specific tags into sub-folders, two examples are that I often tags files with the tags, "Fabrication" or "Microfluidics", which are two sub-folders in my onedrive folder. Mendeley does not allow to sort into sub-folders based on tags but only on, year, author, title and journal.
I'm willing to use a combination of two, maybe three, programs if it works properly and doesn't break down half the time.