What is a good brand of multivitamin? or does it not matter which brand?

There are many: There are many good multivitamins. Find one that breaks down easily in your system so that you absorb the nutrients. Make sure label lists ingredients. Have at least 1000 iu vit d/day; also make sure your vitamin uses natural vit e with tocotrienols. 15000 iu mixed carotenoids, including beta-carotene. B vitamins are important -- folate (folic acid) in mthf form is best. Whole food vitamins are good too.

Does not matter: If you have a specific vitamin deficiency, or desire some specific support,like for menstruation symptoms or pregnancy, then take that specific vitamin. Otherwise, multivitamins are pretty worthless and a waste of your money. They can also be dangerous in some people. For the best results, save your vitamin money and buy a gym membership. Exercise has a proven medical benefit for you.