In neither case is it possible to know what hidden long-term effects they could have on you. But the virus is known to kill and maim people in the short-term at a much higher rate than the vaccine, which is known to protect you from the virus.
For all we know, mRNA vaccines can alter your gametes. We don't know because this is the first time we ever use them. They aren't like viruses or weakened viruses. They are just a massive injection of genetic material (much of it deformed) that encodes a single foreign protein. No human being has ever had such a thing done to them until very recently. mRNA vaccines are not part of any natural process that modern humans or our ancestors have had to withstand to get to the present day.
I don't know why you have this special concern about the gametes. In any case, if there's a significant bump in miscarriages / infertility from the vaccine, we'll probably know very soon, now that lots of younger people are being vaccinated.
First: does the rate at which the cells are made to artificially produce spike protein follow a different curve than the rate at which SARS-2 would? i.e. could mRNA vaccination cause a much more aggressive "inflammatory cliff", thus the huge percentage of "mild" adverse reactions (mild meaning, you feel like death for a day but end up fine with no detectable long-term issues)? It's possible.
And switching to efficacy, while personally I think resistance to the spike protein alone will be sufficient, because SARS-2 does not have the same ability to mutate/evolve the way Influenza does (for example, I can't imagine SARS-2 evolving away from the spike protein), it's very possible that the diverse epitopes produced by real SARS-2 infection give a much more robust and enduring immunity.