Cast iron grates hold the heat longer and produce deep browning lines wich make the meat look very appetising. It may also be used for searing the meat. However, a certain amount of maintenance and care is required in order to prolong the live-span of the grates.
Porcelain-coated grates requires less maintenance but tend to “bubble and flake” with age and usage, which may contaminate meat if cooked over such a damaged surface. A big tip in keeping your porcelain grates in good condition is to wait for it cool naturally before washing. Doing so will ensure that the grate surface will not get damaged from cracking.
Nickel-coated grates are more easily damaged by brushing and scraping. Performance wise, it isn’t that great either so most grillers usually opt for the cheaper but effective porcelain-coated grates, or the trusted cast iron grates. If you do choose to take nickel-coated grates, treat it well after use with gentle brushing.
From our conversations with bbq enthusiasts over these last 10 odd years, it seems cast iron is their preferred choice of cooking surface due to their reliable heating and retention ability. Although cast iron is great for cooking, it can be prone to rust, especially with the humid Singapore climate and all.
Verdict: Try to go for cast iron grates if you can. When you pay hundreds or more for a grill, you’ll want quality cooking performance and that is what cast iron grates provide you.