It's going to depends on the person. The 3-legged stool supporting the answer consists of genetics, lifestyle (including diet) and environment.
For example, a MTHFR C677T mutation will increase need for methylfolate. A MTRR A2756G will increase need for methylcobalamin, B12. Other SNPs play into it, too.
Your need for supplement declines with diets that favor foods that contain these chemicals. My attitude "no meal is complete without something green" and "a sandwich consists of lettuce and tomato, is helped out by good bread, and I don't care what else you put in it, but some protein is good" probably says a lot about what vitamins I need, although I no longer tolerate tomatoes, spinach, peppers, and lots of foods that used to be foundational to my diet.
So, sorry, like many things, a "one size fits most" can be a place to start, but it can't be assumed to be a final fix.