Vitamins are not all created equal
There are many factors to learn about when comparing brand or either multivitamins or other vitamins.
One thing to look at is the form the vitamins come in. Liquid vitamins are not a good choice, tablets not so great either, capsules or powder are ideal
Another aspect is if your vitamin k, b12 or whatever is a natural source or a synthetic version, obviously natural is best, the synthetic versions are not the same.
One other aspect is the amount of each vitamin that is contained per serving. The more the better is almost the case for some vitamins while some other vitamins and/or minerals need to not be overdosed on. But keep in mind more of a less quality vitamin source is not better than less of a higher quality source.
Also there are different elements to each vitamin. For example Vit E contains 4 types of tocopherols, gamma, delta, beta and alpha tocopherols. Cheap vitamins have more alpha (often synthetic) or only alpa tocopherols. If you have too much alpha tocopherols over the others the others will be "bullied" by the alpha and even the natural other tocopherols you get in your foods will not be absorbed/used properly. So you can be taking Vit E and actually have a Vit E deficiency at the same time if this is the case. Mixed tocopherols is what you want, but even companies get away with saying mixed tocopherols and what they do is put 80-90% alpha tocopherols and the rest mixed.
There are also examples like this with other minerals/vitamins, like Vit D, you should be taking Vit D3 but most supplements dont' contain this.
So you can either learn all you can about all this…. or you can just buy a brand you trust and know is all good quality sources and are not synthetic. I personally use and suggest one brand in particular which is AOR Multibasics. We sell this at our personal training centres. It is more expensive of course, you get what you pay for. It's like eating more cheap bad foods rather than eating less good quality foods.