The research indicates that regular caffeine users might experience diminished long-term potentiation (LTP), a crucial process for learning and memory.
Every other other day, both will instantly kill you the moment you ingest any amount no matter how small.
Sometimes I get out my tinfoil hat and think these studies are trying to create more reasons for insurance companies to increase premiums and deny coverage.
The media misrepresents and exaggerates the science.
There's also a problem with p hacking in science. Scientists looking for a correlation and removing all the data that doesn't show a correlation. You end up with what appears a good chance of correlation. However, you don't see all the other data which would suggest the p value obtained is random noise.
Wine is fermented fruit juice. So it'll have benefits of eating fruit and consuming fermented products. It also has alcohol which is bad for. If we mixed bleach and medicine it we would also find benefits from consuming some of such a mixture, we would also find lots of evidence that consuming it is bad for you. The sensible thing would be to only consume the medicine and not the bleach, but that would never make the headlines.
Additionally many observations in health studies correlating lifestyle choices can be associated with income/class. Those with higher incomes tend to drink wine rather than beer. They also consume more coffee. People with higher incomes tend to live longer and healthier life's (less stress, better healthcare, better living environment, more leisure etc), they also drink more coffee and wine.
Personally, red wine gives me a headache and coffee makes me anxious. So I don't care what these inconclusive studies say (positive or negative), for me personally both are bad (though I still do drink coffee). I think people should ignore these inconclusive studies and do self-experiments instead, until we have better data. Most people have a baseline level of being hyper-caffeinated and can't imagine life without it. Life could be better or it could be worse, but people don't care to experiment.