I couldn't find any solution that works for what I want. Google Drive is the most similar to what I want (with a minor difference that bugs me). I want an external virtual drive on my computers that syncs my file on demand, that doesn't count against my hard drive quota (unless I download and work with these files).

Google Drive gives me that (I pay for it) and all my files are synced across all my devices. My problem is that I do not want one device to be "the owner", I want all devices to be the same because. Unfortauntely Drive doesn't allow that. So on the main device I can access the file in their local path, while in others they are in (for example): G:\Others computers\Laptop\Drive

I hate that the files are inside "Others computers\Laptop", because it makes me feel that if I ever lose the "Laptop" and lose access, I may lose all my files.