Hey, sorry I didn't see this earlier. I figured mdapps would send me an email or something. I don't have any MD acceptances at this point but I do have a couple DO ones.
It's hard to say what EC's set me apart. Since I'm older than the average applicant, I had a lot of time after undergrad to do counseling/advising things to people who need help. I really liked doing that though so I recommend finding something that would let your "eyes light up" during an interview. Also, I made the mistake of having too many different EC's. I think it's important to have a theme. Despite my best intentions, some people I talked to thought I was boxchecking, which wasn't true at all but I realize that people could see it that way.
The SMP did help but it's important to do well. I lucked out I think. Normally a low SMP GPA like mine doesn't bode well. Depending on the program, 3.5+ is basically what you need. I also had a ton of research and volunteering.
I hated delaying my application a year and I hated having to reapply but taking a year off or time to improve my application helped a ton. If you are in that kind of situation, I would err on the side of taking time off to do what you need to do.