I wouldn't focus too much on that--at least for yourself. You won't necessarily get an mRNA vaccine. The first two vaccines are mRNA based, but there are a bunch of others right behind it that aren't. The Oxford vaccine isn't and cheaper to produce. Since the Pfizer vaccine has all of the logistical issues with temperature storage (it not only has to be transported at -20 degrees F, it has to come to room temp before injecting) it will probably only get used at designated sites for people with higher priority. I heard someone say most non first-world countries likely won't bother with the Pfizer vaccine at all.

I believe Pfizer and Moderna are mRNA based vaccines. The Oxford and Russia's Sputnik V are adenovirus vector vaccine.

https://www.vox.com/2020/8/13/21359025/coronavirus-vaccine-c...