This recording was voted the best Berlioz Requiem in the Radio 3 "Building a library" programme. Unfortunately at the time it was part of an 11cd Berlioz set on the Brilliant label.
It's a wonderful recording and worth your money, though I'm not sure I'd say it was the best. It's certainly Grand in sound and mood. But I have to confess I prefer the Previn EMI recording, even to the classic Davis or the later Munch recording.
NB: I don't pretend to have heard ALL the available recordings of the Berlioz Requiem, you understand, but I name those I feel worth a mention. Apologies to Maazel, Dutoit, Levine, Barenboim, Ozawa and Shaw.
Berlioz is mostly famed for his Symphonie Fantastique. One could argue that this piece is actually his master piece (he thought so himself anyway). The final few movements are astonishingly atmospheric and in many ways quite unlike the "standard" Requiem.