There is an influx of info online, but none of it is helpful
Best way to determine this is to do a physical with your doctor and get a blood panel done. Usually the CBC, comp metabolic, etc should be relatively cheap if you have insurance. That will tell you what you’re deficient in and you can go from there. If you want to just take a general multivitamin that’s fine as well. There was a good website that showed you the best supplements based on the actual value of how good the sources of the vitamins were and the science behind them but I can’t find it at the moment.
Just track your diet using Cronometer for a month.
You will soon see what you are lacking, ideally change your diet so you don’t need vitamins.
I found that no matter what I do I can never get enough magnesium or omega 3 so I take magnesium and fish oil tablets.