As one who never misses an opportunity to add a Spencer Tracy film to my collection, I must admit that I am a bit prejudice because of my view that he is, perhaps, the finest American actor of the 1940-1960 era. But, unlike the other reviewers I much preferred the Tracy version of the story. First, while some of the technical flaws of the Frederick March version may be due to film degradation, it is also clear that sound recording in the 1932 version was far more primitive, something you'll especially notice in scenes where there is movement across a large set. By 1941, not only had the sound recording improved substantially, but the visual aspect of film had also evolved.
But, my preference for the later Tracy version goes beyond that. To me the more subtle characterization of Hyde by Tracy captures the reality of the evil side of real people. March's transformation is excessive, more like one would expect from a horror movie, while Tracy seems to be saying that the average man is not grossly different at his best or worst, that it takes little to tip the scales. In particular, the final scene with Lana Turner, you know he is transforming from lover to murderer without ever seeing his face.
It's remarkable how very similar the scripts are for both versions, so I suggest watching them in chronological order. While I prefer the Tracy version, I appreciated the opportunity to see and compare the two. And, BTW, you will notice that it would seem more logical for the female leads in the Tracy version to be reversed, but both Lana Turner and Ingrid Bergman turn in fine performances, as opposed to Miriam Hopkins (1932) whose performance is a bit over the top.