portable hard drive, seagate or western digit of better quality build?

In 2007 I bought a Dell 1720 Inspiron and installed two WD Scorpio Black drives in it. After 10+ years of 12-15 hrs a day 7 days a week use I just replaced them. Not because they failed but just slowly upgrading the Inspiron to keep using it as an extra lappy. So from my use I would say WD drives, but I would consider the other replies since perhaps they have lowered their manufacturing standards with the soldered components.

It's funny, i noted earlier how I had never had either a Seagate or a Western Digital fail, well when I got home today my son told me the external hard drive on the Xbox One died. Sure enough, Seagate 2TB drive was dead. It was only about 6 weeks old, Seagate is replacing it.

Seagate does not have a perfect reputation:
Seagate slapped with a class action lawsuit over hard drive failure rates | PCWorld

I have 3 basic 1T & 2T Seagate Expansion drives and I've had no problems.

I generally use WD drives as I find them quite reliable.

That being said, most external drives in my experience are of low quality and failure prone. A casual look through the Win 10 or Win 7 forums will confirm this. There are a number of new "External HD failure..." threads every week.

If size or portability is not an issue, you are better off to buy a desktop drive and put it into a well ventilated enclosure. It will last a lot longer than a portable.

Just my $0.02