If these vaccines are meant as a form of population control, then they do a pretty crappy job of it. Neither COVID-19 nor vaccines have made any significant impact on population growth.

While I have not been vaccinated yet, if I end up getting it for one reason or another, I actually lean towards the Johnson and Johnson variety. As I understand it, that one is based on the same process they use to make the flu vaccine. And whatever risks the flu vaccine carries, they are pretty low. I'd have to do more research though to see what makes the J&J COVID vaccine supposedly more likely to cause blood clots. mRNA vaccines on the other hand do not have nearly the history of testing as more traditional vaccine types. Until recently anyway since they have decided to test then on the population at large.