I do like that SpiderOak allows syncing from ANY folder, not just one (plus subfolders) the way my current Dropbox does. And I also like their versioning feature, although Dropbox does keep a few versions back as well.
I know there’s at least one relatively expensive aftermarket utility (Boxifier) that allows Dropbox to sync any folder, as well as various schemes using Symbolic Links to fool Dropbox, but those all seem cumbersome and disaster prone to me – it’s relatively easy to delete a symbolic link and have the folder to which it points magically deleted as well.
At $40 a year for 1TB, I’d give SpiderOak a try, but that $130 a year after the first year ‘trial’ is a killer for me.