As we’ll talk about in a moment, speed wasn’t the only factor we considered, but it was the most important. Using our external hard drive reviews, we’ve narrowed down the five fastest external hard drives we’ve seen. In this guide, we’re going to run down the fastest external hard drives we’ve tested. Although you should factor in build quality, capacity and features depending on your use, the crux of what makes an external hard drive worthy of our best external hard drive guide is how fast it is. Speed is king when it comes to external hard drives.