I currently use a Mediasonic USB 3.0 stuffed with 5 TB Seagate ST5000DM000 drives. This is my second Mediasonic (I used a FireWire 800 version filled with 2 TB drives, perviously), and I've been very happy.
I got a drobo 3 so that I could move my drives over. That was handy. The power supply died on it 3 months later, and dealing with their tech support was super annoying. but it did get worked out. It's still not the fastest, but it is convenient. If I were doing it over, I dunno what I'd do.
I am really happy with my Synology NAS, a 1512+ so it is a few years old. The Synology software, DSM is very easy to use and has been rock solid for me since it has been set-up. Initial set-up can take a while depending upon how much data you have to transfer but it has been plenty fast for my needs in everyday use.