Ask HN: Backing up/syncing files to the cloud?

I have about 300 gig of files on my hard drive and generate about 100/150 files or ~500MB of data every day. I've been looking, rather fruitlessly for a way to automatically back these up to the cloud (S3/Google Drive/OneDrive/B2 - anything). The caveat though, is that I'd prefer to delete some large files from my local after a while, but wouldn't want to wipe it off my cloud drive. I've been looking for ways to do this but I'm unable to find something that fits my workflow. Client side encryption is a good to have, although isn't a deal breaker.

I remember Bitcasa having something like a 'cloud drive' option where it selectively downloads the files you need when you need it. This is exactly what I need! Unfortunately they're not around anymore. Any ideas on how I can go about this?