GPA
1st quote: "one score on a test does not trump or void three to four years of hard work"
2nd quote X (every single school I interviewed at except two): "yes we do go back and look at scores again when we make our final decisions. Would you really want us to judge you based on a couple 30-minute conversations as opposed to 3-4 years of hard work?"
In my experience this cycle and based on "3-4 years of hard work" statements that came up whenever I asked this question to adcoms, it seems that GPA's easily the most important factor. The MCAT is there merely to put your GPA into perspective.
To be honest, you need a good GPA AND a good MCAT to do get interviews and get accepted. And even after the interview, many schools will look back at scores and compare with other candidates. The whole "once you get an interview, everyone's on the same level" myth on SDN isn't quite true =/. With good extracurriculars, you have a shot at getting a better interview score, but...that's just part of the process.
- In rare cases, the single most important factor CAN be your recommendation letters if you have an extremely baller professor who has a connection with the specific school you are applying to write you a glowing letter of rec...or you can get 20 first author publications in nature...or solve world hunger