Ask HN: Is there any alternative to Dropbox?

I have been using paid Dropbox for 4 years. But in the recent year, Dropbox has added a lot of unnecessary features to the tool that slow down my machine significantly. I really don't like that. I only want a plain simple file synchronization app that works for files, symlinks and UNIX permission. That's it. I don't need friend list or complicated document collaboration feature. This is personal use only. I don't mind paying money but I don't want to buy pain.