There are a number of types of BBQ cooking grids on the market. It can be confusing to try and choose the best option when buying a new grill. What ends up being the best grill cooking surface will depend on a number of things.
It really depends on you! Whether you want sear marks on your steaks, how much you have to spend on a grill and how much maintenance you are willing to do. It may also depend on your preferred cooking tools and how tolerant you are of your food sticking to the grill.
Generally as a principle, the heavier and thicker the grill is, the better. It will take longer to heat, but will hold the heat better. It also will take longer for corrosion to thin the grill until it is unusable.
Here are some of the grill options with the main pros and cons.
Chromed or untreated steel
The thin shiny metal grills you remember from your childhood are really not recommended unless you have an extremely limited budget. The main advantage is they are cheap and light and you should not pay more than $100, or really even $50 with a grill that has it, as its lifespan is very short.
Once heated it tends to rust and flake on the surface and the pitting can cause your food to stick, further damaging the grill on removal. If you get more than a season from one of these you have done well, and you have to be careful not to serve up any degraded grill in your food.
Cast iron cooking grills are generally very effective for outdoor cooking, giving great show-stopping sear lines when thick and heavy. Some users can find the heavy weight of the cast iron grid dangerous especially when it is hot and they need to replace charcoal, so bear that in mind.
Main cons are the fact that untreated cast iron eventually rusts, partly due to the heat, partly due to the moisture of cooking and the environment.
So, cleaning and oiling all over, like you would for a cast iron pan, is really required for easy non stick cooking, avoiding rust in your burgers and for the longevity of the grill. Also bringing the grills in out of the elements, whenever possible, helps, but is not always practical. If you are not prepared to do this but have a decent budget, a porcelain-coated grid may be a good option.
Porcelain coated cast iron
This is a slightly more expensive option, but if you are gentle with it, the better quality porcelain grills do protect the cast iron grate from rusting and degrading over time. Lifespan maybe 3-4 years.
You get all the advantages of great heat transfer, low maintenance, with less sticking of food to the grill, but care must be taken when using utensils on the porcelain surface as it can be damaged or chip if you are rough with it with metal tools and it will then quickly rust. Watch for cheap grills with this option as the porcelain may be thinner and more likely to chip.
If the stainless grate is thin or poor quality (inexpensive) these tend to degrade quickly, lose their non-stick qualities and are only worth having if they are of a higher quality thick heavy weight manufacture, easily tested with a magnet not attracting to the good ss. And they are worth having.
If your funds are limited to a new grill under $1000, porcelain coated cast iron may be a better option. For those who can buy the Cadillac of grills, the thick high quality stainless is easy to clean and use, and gives a good heat transfer, can be non-stick, the main downside is cost is significantly more than the other options. Consider a 1/4″ diameter stainless grill a minimum, but 3/8″ stainless is better.
What is really comes down is personal taste and experience. And BBQ aficionados have to agree to disagree! Many try one thing then switch to another when that finally breaks down.
None of these barbecue grate materials are perfect and due to the temperature extremes and moisture rigors they are put through while creating delectable meals, there are pros and cons to each type. Hopefully this gives you an idea to help you decide.