It doesn't really matter in any significant way to you if you're a normal person with a decent enough diet. The overwhelming majority of your vitamins should be obtained directly from your food, the multivitamin is more of a "cover your bases" supplement to take in case you're a bit low on some particular vits or mins.
There's absolutely no need to spend much money on a multivitamin, I'd recommend finding something under or around $10 for at least a couple months' worth.
Also, abstain from the super high dosage approaches, whether ridiculously high-strength pills, or taking multiple dosages of a normal multi in one day. There are many vitamins and minerals that you DO NOT want to be taking way more of than recommended, so that multivitamin-shotgun approach is definitely not optimal here, if you need to supplement way high on some specific vits/mins then go grab that separately, don't just take a super strong multivitamin preparation.
Oh, and on the note of "greens" drinks/powders, these can be good (and terrible) products, but the majority of them are NOT a substitute for a proper multivitamin, despite containing some vitamins/minerals. One that is designed as a multi should say so, and I'd just double check it against another, regular multi to be sure it's not missing anything.
Oh, and for brands, I wouldn't buy a no-name product, as there is very little oversight of nutritional products. I'm comfortable as long as it's a national brand that's got some history in most cases, even if it's flinstones chewables - just to have the reassurance they're unlikely to risk their brand by skimping on ingredient potency or having contaminated products, both of which are regular occurences in multis/supplements (especially in herbs, that's a real bad specific area for that shit).