I had in my collection Richard Hickox's recording of this alongside Solti's rendition. I was then told that, apparently allegedly etc, that Sir John Eliot thought his recording of Verdi's Requiem was his finest recording to date, so I had to buy it.
It is true - the performance of the Requiem and the four Sacred pieces are masterful. The Dies Irae, that most famous moment, is typical Gardiner - punchy and driven with no let up - 'day of wrath and doom impending' indeed. However, in the more gentle moments, such as the opening and later in the Libera me, Gardiner weaves a beautiful serenity into the performance.
The test for me with this piece is the 'Domine, libera, Domine' at the very end with the almost-Spanishlike dance where the fugues of 'cum iudicare' build up into a full choir & orchestra frenzy, the soprano soaring high above them - the frenzy is manic, but superbly controlled by Sir John Eliot. Gardiner's choice of soloists is superb, especially the soprano Luba Orgonasova, whose voice matches the music perfectly.
Even if Sir John Eliot didn't say it was his finest recording, there's every evidence here to suggest that it could be.