Among the options you mentioned, the most popular way to cook a turkey these days is typically roasting it in a conventional oven. While each method you listed has its merits and can produce delicious results, roasting a turkey in the oven remains the traditional and widely preferred method for many people. It allows for a nice golden brown skin and even cooking throughout the bird. However, it's important to note that cooking methods can vary based on personal preference and cultural traditions. Some people may choose alternative methods such as deep-frying or using a slow cooker (crock pot) for convenience or specific flavor preferences. Ultimately, the "most popular" method can vary depending on geographical location, cultural background, and personal tastes.