The answer to this question depends on what you are looking for out of your grill. Cast iron grill grates are great for searing and browning food, and they heat up quickly and hold that heat well. However, cast iron grates are prone to rust, so they require more maintenance and upkeep. Porcelain grill grates are less prone to rust and require less maintenance than cast iron grates, making them a more convenient option. However, they don’t retain heat as well as cast iron, so they may require more fuel to get and maintain the desired temperature.  Ultimately, both cast iron and porcelain grill grates have their own pros and cons, so it’s important to consider what type of grilling you plan to do when deciding on which one is best for you.