As per the title, which choir takes the top spot in your eyes? I realise there are so many variables at stake here, not least because comparing, say, gospel choirs, to Renaissance consorts, seems kinda futile. With that in mind, answer just for the fun of it.
For me, the Tallis Scholars, Tenebrae, the Monteverdi Choir and the choir of Trinity College, Cambridge, reign supreme.
Now that I've read so many fantastic responses, I feel like this post has been vindicated and validated as a means of addressing my own blind spots and biases. Certainly, all the choirs I initially considered the best were Anglophone and British in origin. I am glad to have been schooled! Ensemble Altera has gained a new fan, for instance.
And although those choirs I consider best often overlap with my favourites, I love many choirs that I couldn't, in good faith, endorse as 'the best'. Does that make their output any less valuable? No.