The winner of this game VS. an undefeated Florida Gator team will be bigger. That will be two top 5 teams, and the best 2 teams in the SEC, whoever it is.
What makes you certain that Florida will be undefeated when they meet Georgia? Also, what makes you think that Florida will even play Alabama? There is this other team named LSU that won a national championship last year and is still undefeated in the top 5 of the country that plays Florida on October 11th. By far, that game is the biggest one of the year so far. It's not even a question, unless one of the two teams absolutely lays an egg in the next two weeks.