I'll admit I prefer to see original characters (or at least pastiches of two distinct characters), but that's because my players have spoiled me rotten. If I pitch a baroque Gormenghast-like fantasy, they come up with bizarre librarians and clockworks. If I throw out "superheroes, but with covert mystical origins" as an idea, I get college students on a first-name basis with Thunder God Indra. Living paintings, surly G-Men, heavenly swords forged into human form, drawing-room-comedy necromancers — I admit I take a lot of delight in seeing just what in the world my players will come up with next.
That said, even if I did feel slightly disappointed with a new player coming up with a derivative character, I would do my damnedest to get over it. For all I know he or she would be knocking all my expectations out the window three sessions down the road. It's happened before.