They were incredibly different artists and Gaga already has more albums than Amy did in her short and tragic life. Amy had a better voice, Gaga is much more creative imo.
I love GaGa more than Amy, but I think some of you are exaggerating GaGa's skills as a songwriter, especially compared to Amy. Funny thing is, had this been any other singer compared to Amy, Amy would get more votes on the songwriting tip.