Take all the B vitamins, not just a few. They work together, so you need all of them.
But some have more to do with weight loss than others. You need choline and inositol to break down fat tissue. You can get a lot of choline by taking lecithin capsules, and inositol you can buy as tablets or capsules.
You also need a lot of magnesium for fat metabolism. If you're going to take supplements, go for magnesium carbonate or magnesium glycinate. If you can find magnesium chloride as a supplement, that would be good. These are the easiest forms to absorb through your digestive tract. Magnesium sulfate or magnesium chloride can also be absorbed through your skin, by throwing a handful or two into a bathtub full of water and soaking yourself in it. I don't know if you can get enough that way, though -- it's not my usual method.
You can also eat foods that are rich in magnesium (this is my preferred method). The dark green leafy vegetables are the best -- spinach, kale, chard, dandelion greens, and seaweed. Nuts and seeds are probably the next best source. Most vegetables and fruits have some magnesium in them, so the more of these you eat, the better. They also contain other nutrients that are important for the health of your hair and skin and all the rest of your body.
That's my two cents' worth.