Reddit mentions of Nature's Bounty, Super Strength B-12, 5000mcg, 2 Oz (Pack of 2)

Greens for vitamin A, C, and K. 3 cups daily of kale, or a bit more of other greens, will do.

A source of vitamin E in its alpha-tocopherol form (aim for 10 mg). Cooking with 2 Tbsp of a higher vitamin E vegetable oil (like canola, sunflower, or safflower oil) or 2 oz of almonds would cover this. Not neccesary every day, but on average.

Most importantly, B12, as while the adverse effects of most micronutrient deficiencies are reversible, the first symptom of severe B12 deficiency you may notice after a couple years of a B12 deficient diet is permanent neurological damage. While the requirement is only 2.4 mcg, if one's supplementing once a day or once a week, due to details of absorption it makes sense to take 100x as much: 250 mcg/day, or 1750 mcg a week. A $7 bottle with 300 mg cyanocobalamin, consumed over the course of a year, is about the right dosage.