I have this vinyl boxset, and a CD boxset of the Prestige recordings. Although I haven't listened to either in over a year, the vinyl sounds warmer and more pleasant. If I remember correctly the nice thing about the CD boxset is alternate/and or additional songs. I think Analogue Productions released these titles in both 33 & 45 rpm editions individually. I can't guarantee, but theoretically the 45 rpm version would be the better sounding version.
Also Analogue Productions is re-releasing some of these titles again as part of their Prestige re-issue series. Which is being mastered by Kevin Gray, cut at 33rpm, and pressed at QRP on 200g vinyl.
I look for original pressings whenever I can, and if available I also pick up an audiophile copy. However I'm not sure how much can be done when it comes to SQ concerning the Prestige catalog. It's one of those buy it because you love the music, not because of the high fidelity things.