I was just listening to the Evgeny Mravinsky recording of Tchaikovsky's 6th Symphony today, and it is so much better than the other recording I have of this work. It's funny, when most people want to buy a classical recording, they don't pay any attention to the conductor, orchestra, or the actual performance itself. They just want to own the symphony. Yet they would never think of buying a cover of their favorite artists' works instead of the original recording itself. Odd. There's such a large difference between recordings of classical pieces.
The conductor has a huge impact on the recording. The same influence a director has over a film. Many people will go see a film just to see a movie star (Julia Roberts' success is proof of that). But I go to a film primarily on the strength of a director. The correlation between a director and the quality of a film is much higher than that between the cast and the quality of the film, once you reach Hollywood production budgets (in home movies, the poor acting can be highly distracting, it's true). Same for the chef versus the wait staff at a restaurant. It isn't always the case, but in classical recordings and movies, I have absolute faith.