My company "flip-flops" between FTP & Buzzsaw.
Depends whether or not the client will pay the costs.
To be quite honest "Buzzsaw" is really just a FTP site with HUGE controling features of who gets to see which file & which folder.
But if that's case then why pay for it when you can just setup multiples FTP sites for little cost. Each site can have it's own password and user name for EACH project.
I mean if you're all on the same project then why hide specific files & folders.
There is the honor systems.
Anyway .. that's my 2 cents.