Bernstein was accused of being too much "in the way of the music," instead of "letting it speak for itself." I prefer his cycle of the Beethoven symphonies above all others. His was a strong personality, like Glenn Gould's, and the world would be missing something phenomenal if he'd just tried to be a musical scientist.
At the other extreme is Pierre Boulez, who, though he's just as strong a personality, can take almost anything he conducts and turn it into modernist or post-modernist music, yet another fascinating thing.
Then there are those like Tennstedt, Haitink, Kubelik, Szell, Charles Rosen (piano), who exist somewhere in the middle. James Levine, with the Met: a history in itself.
I think it's simply a question of whether or not, like various kinds of reproduction systems and transducers, you are looking for "neutrality" on the part of the performer (is there ever such a thing, though?), or whether you want the imposition of a strong perspective and idea, to guide you.
Your own familiarity with the repertoire can change that, over time; the more imposing performers will increasingly tend to make everything sound "like them," leaving you craving for something different. Those who are more intimate with study of what they conceive as the composer's intention -- however construed, and make no mistake, this is still interpretation! -- are still constructing a picture of whom they think the composer is. A powerful objectivist can still present a performance as a vision, one separate from her/his own personality, but still coherent, gripping, thought-provoking.
The worst, though, are those whose performances aren't inspired by anything except obedience; I think increasingly, as time has moved on, the newer generations of performers have been all too obedient in their approach to the repertoire, to performance practices, to what they naively conceive of as a more "objective" approach.
It's time for a new generation of musicians to rebel, truly rebel, within the tradition.... and use it to say something! Anything!
