they are free from chemicals, they re-heat your food more evenly, they keep your food fresher, they are more environmentally friendly
plastic containers are cheaper, lighter, and are still fairly durable. they are a great choice when you are hiking, or if packing lunches for your kids. make sure you pick one that is BPA-free
dividers are essential for when you want to keep certain ingredients separated. they are great because often you can fit your entire lunch in the one box and have snacks in one compartment and main course in another.
pros of stainless is that they will not break if dropped and are safer for kids. the cons? are expensive, you cannot heat them in the microwave, and they are not 100% leak-proof.
there are a ton of kid-friendly options on the market. I prefer a bento-style lunch box because it means less containers to wash and less likely we will lose containers/lids etc
these containers will keep your lunch at the right temperature so you a) don't have to reheat it or b) don't have to worry about it going off on your way to and from work.
don't forget about your sauces, dips and drinks! here are some cool accessories that will take your lunch to the next level.