After the 3TB was full I use a 4TB drive now for backup. Both are a Seagate Backup Plus Desktop Drive USB 3.0. They come with a backup softare installed. I do an incremental backup each week that takes usually less than 10 minutes, a full backup takes several hours. The advantage of the new backup software generation is that files are no more compressed. Each file is directly accessable. So if you destroy one of your files -- or even an entire drectory -- it is quite simple to restore that one.

I also have a portable USB 3.0 drive Toshiba "S-3600 - A" that was given to me. I use this one as a backup for my laptop. All the necessary softare is installed to run my installations using another laptop if mine fails. (I know some people who do have a second laptop for backup purposes. I'm not there, yet.)

Especially for backup purposes I do not recommend cheap drives. I prefer to use reliable drives from manufactureres with a good reputation. There are tests and reviews out there. And often it takes a while until a manufacturer with a bad reputation builds up a good reputation.

Guido

Desktop; i7-2600k, 8 GB mem., Win 10 Pro, BIAB 2017; RB 2017 - latest build
Laptop: i5-2410M, 4 GB mem, Win 10 Pro, BIAB 2017; RB 2017 - latest build