The answer is: it all depends. In this case, it all depends what you want to do with it.
The Douay is certainly lovely and historic. If it’s what you’ll read and enjoy, go for it. It’s great for devotional reading if you can handle the older English.
But as a translation, if you’re wanting to do serious textual study, it’s not preferable. It’s a translation of a translation, i.e. it was translated from the Latin Vulgate, which itself was translated from the Hebrew and Greek texts available to Jerome, at least originally. This is to say nothing of the textual history of the Vulgate itself. You have to take into account as well that there have been many, many finds of manuscripts that have helped to fill out our understanding of many passages and how to best translate them. Chief among these finds is the Dead Sea Scrolls, in 1948, more than 3 centuries after the Douay was published. There’s also the Cairo Genizah, a lesser known, but still significant find. In both cases, as well as in other manuscripts and fragments discovered in the intervening centuries, there has been much to help make our translations more precise.
So the Douay is beautiful and is fine for devotional reading if that’s your cup of tea. But for textual accuracy for more scholarly purposes, the RSV is a better bet. It’s what I use when I want to know what the Greek and Hebrew say without having such at hand.
-Fr ACEGC