The Beatles released a UK only version of "The Beatles" in mono. In the US, "The Beatles" was released in stereo only. So unlike the previous albums, the stereo version of the album was indeed the first priority. To my ears, I think the stereo version sounds a lot better than the mono version. The general consensus is that the stereo version is better.
Most everything prior to "The Beatles" is probably best heard in mono, in particular, "A Hard Day's Night," "Revolver," and "Sgt. Pepper's Lonely Hearts Club Band."