Know what you are getting.

(But take what you can get.)

There are several vaccines in development for COVID-19.

The most notable of these are from Pfizer/BioNTech,

Moderna, AstraZeneca/Oxford, and Johnson & Johnson.

The development of these vaccines is remarkable in more than one way. First is the speed of development. Next are the underlying new technologies.

Any vaccine is better than none -- take the first one you are offered. 

If you do have a choice, make an informed choice.