I have 35mbps upload from the ISP, and limit each stream to 8mbps. This covers direct streaming all my 1080p content and a 4K transcode as needed.

I currently have 6x10TB of these drives running in a gluster array. I’ve had to return 2 so far, with a 3rd waiting to send in for warranty also (click of death for all three). That’s a higher failure rate than I’d like, but the process has been painless outside of the inconvenience of sending it in. All my media is replaceable, but I have redundancy and haven’t lost data (yet).

Supporting hardware costs and power costs depending, you may find larger drive sizes to be a better investment in the long term. Namely, if you plan on seeing the drives through to their 5 year warranty, 18TB drives are pretty good value.

For my hardware and power costs, this is the breakdown for cumulative $/TB (y axis) over years of service (x axis):