The 1943 original cast (Decca) is an essential CD because it documents the show when it was new. It is not note-complete: most of the dance music is missing and several songs have lost verses here and there. Even the Finale does not represent the way it is done in the show, but it makes for an excellent album that never wears out its welcome. The recent Decca remaster is taken from the original 16-inch glass masters and has good high fidelity mono sound.
The best sung version is the film soundtrack (on Angel) with Gordon MacRae and Shirley Jones. True the orchestrations have been enlarged, and two songs were eliminated, but it does give an enjoyable listen. The current edition includes extended dance music that was left off the original album.
The most vividly theatrical version is the 1979 revival cast (RCA Victor) and I like it quite a bit but I do find some of the performances a little too over-the-top. Being made in 1979 the sound here is much better than the original 1943 cast album and it does use the original orchestrations.
I also enjoy the Hugh Jackman London revival (First Night) quite a bit but the re-orchestration is bothersome. Not that it is bad but it is not an improvement over the originals. Also Susan Strohman and Trevor Nunn fiddled with it adding extra scenes and changing the original choreography. (The British for some reason feel the need to "improve" classic American musicals. They recently re-did MY FAIR LADY and SOUTH PACIFIC. I wish they would stop!) This is however the most complete version available on CD.
You really can't go wrong with any of the above.
You CAN go very wrong with the studio cast starring John Raitt and Florence Henderson (SONY), which is a really awful version.
An older Columbia studio cast with Nelson Eddy was out on CD (SONY, again) but seems to have been withdrawn in favour of the John Raitt stereo recording. It's no great loss but does offer a more complete reading of the score than Decca's set, but the cast is not exciting.
Also avoid the 1980 London revival (JAY) taped live in the theatre. The cast is no--name and the performances are dull.
As for the 1947 London cast with Howard Keel, (Angel) it is just a 16-minute medley of songs none of them complete nor in the order they appear in the show, so it's a useless recording.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com