The perception that some vaccines may be better than others has to do with the topline numbers from efficacy studies. The mRNA vaccines from Pfizer and Moderna were both found to be about 95% effective against preventing symptomatic COVID-19 after the second dose. The Johnson & Johnson vaccine, by contrast, was found to be 66% protective against moderate and severe disease overall worldwide, and 72% protective against such cases in the U.S. They are doing a lot of dancing to try to say this number doesn't really matter. If the number is accurate, then for every 20 unvaccinated getting ill there would be 1 on the Pfizer or Moderna vaccine getting ill or 6-7 on J&J. I'll take the one where I have 1/6 the chance of illness if I have a choice.