I must admit that my favorite Messiah is the Beecham recording from 1959. The LP issue is stereo but was cut at too low a level, and was noisy, but the CD reissue is greatly improved, and responds well to 3-channel or multichannel playback. Sometimes derided as the "big band" Messiah, the CD set is accompanied by an essay by Beecham explaining his interpretation of Messiah. It's worth buying the CD set just to get this essay. Very well thought out.
In Handel's time Messiah was performed in many versions, often with an ad hoc orchestra consisting of whatever musicians were available. Meanwhile the chorus swelled to as many as 3500 voices! Over time the chorus was shrunk down to a more reasonable size, but most performances stuck with the "authentic" small orchestra and simple orchestration. Beecham points out that the development of the symphony orchestra has accustomed the ear to a richer and more varied sound than can be delivered through voice alone, and it has become tedious to listen to people singing for an hour and a half. Beecham's Messiah uses expanded orchestration by Sir Eugene Goossens and an orchestra of about 150. The soloists are world class..Jennifer Vyvyan, Monica Sinclair, Jon Vickers, Giorgio Tozzi. I have heard many performances of Messiah, and while I always enjoy them, even the little version put on by a local church, I always have to go home and put on Beecham. Whatever your preference for Messiah performances, you ought to have the Beecham as a reference. It is a milestone in the history of this composition.