If backup capacity is of the utmost importance, Seageate's Expansion desktop drive in 8TB form is the best external hard drive for the money, even more so now that it is on sale. Over at Newegg, you can snag the external HDD for $169.99—just use coupon code 93XRN55 at checkout for the full discount.
This is the version that comes bundled with Rescue Data Recovery Services, and together the combo goes for $229.99. However, Newegg has the package on sale for $199.99, plus the above promo code knocks another $30 off the price, saving you $60 without any mail-in-rebates hoops to jump through.
Rescue Data Recovery Services is a big value addition here. The way it works is, if the drive goes belly up for any reason while under warranty, you can file a claim to have a team of pros try and extract your data. Seagate even hooks you up with a prepaid shipping label.
The turnaround time is up to 15 business days. Seagate says its in-house data recovery service boasts a 95% success rate, but in the event it can't recover your files, Seagate will either "destroy your drive in a secure and environmentally friendly manner or return it" to you, whichever you prefer.
It doesn't matter how your drive died, either, whether it's a mechanical failure, an accident on your part, or a natural disaster like a flood. If you can no longer access your data, Seagate will attempt to retrieve it for you.
As for the drive itself, it's an 8TB HDD stuffed into a portable enclosure with a USB 3.0 interface. You'll get around 150MB/s for reads and writes, which isn't particularly peppy (compared to an SSD), but it's a lot of space to potentially back up multiple PCs.
