Personally, I would rather listen to a solid, heart-felt performance than a perfectly engineered, but rather sterile, performance. I was watching a series of movie clips of Judy Garland the other day. The host of the program told of how Judy Garland was known for doing her sections of the enormously complicated production numbers in one "take." She put so much heart and soul into the performance that though the pitch or quavering of the voice might not have been completely perfect, the overall effect was brilliant. Audiences loved her for the moments when her performance tugged at their heart-strings or brought tears to their eyes. No amount of editing can put heart and soul into a performance. Only the performer can do that.
Now, I am not saying that I enjoy sloppy diction or lazy pitch. But I am saying that a performance devoid of spirit and soul is no performance at all. Whether singer or instrumentalist or chorus or composer, the song's "gotta come from the heart."