J&J vaccine

The CDC just announced the pause of the Johnson & Johnson vaccine in the U.S. because of six blood clots among seven million people vaccinated.  If you're shaking your head trying to figure out why the CDC pulled a life-saving vaccine after a few adverse events so rare -- where you'd have a much greater risk from dying from crossing the street or getting into a car -- you are not alone. Is the U.S. shifting regulatory policy to the Precautionary Principle?
As the news cycle brings us more COVID-19 variants and reports of the efficacy of the new vaccines by J&J, Novavax, and AstraZeneca, you have to wonder which vaccine is best and why.