Hi @Charley,
The choice of the HDD, it all depends on your requirement and your budget. In terms of reliability, WD drives are good and have; the less failure rate. I’d suggest you to go with the WD My Passport Ultra because it has the extra feature like software for backup and security. Its a simple storage drive and best for budget. It comes with the full version of the WD SmartWare Pro software. It's a pretty simple and straightforward backup software that uses minimal PC resources. Set it up once and you can forget about it.
For more information about WD External drives, you may visit the below link:
Support Answers
Hope it helps