Different people will have a different opinion on what constitutes the best barbecue marinade. This is largely because it depends on what is being marinated, what the desired end flavor should be and the personal tastes of the chef and the diners. Certain meats, such as beef, benefit greatly from a marinade in a number of ways, including tenderization. More delicate meats, such as chicken, can be marinated to add flavor, especially citrus flavors, which they pick up very well. The best barbecue marinade will impart exactly the right flavor, at exactly the right strength, without compromising the texture or appearance of the food being grilled.
Steak, particularly beef, tends to have a larger amount of tough cuts than most other meats. A good beef marinade should have a high amount of acidity so it can loosen the tendons and connective tissue between the muscle masses to make the meat tender. One ingredient in a tenderizing barbecue marinade can be liquor. Distilled liquors such as whiskey can be very effective tenderizers and add the flavor from the wooden barrel in which it was aged. Vinegar and beer can serve the same purpose because of their acidity, although vinegar will add a tart flavor that can be counteracted with sugar or a sweet ingredient such as honey.
Chicken usually does not have problems with being tender but faces the challenge of remaining moist on a grill, because it has no real amount of fat on the inside. A chicken barbecue marinade that can help to preserve moisture should have some salt and a lightly acidic ingredient such as citrus fruit. Through the marinating process, water will be drawn out of the chicken and replaced with the marinade, so the taste need not be overly strong, as it can be with steak. One type of barbecue marinade that works well with chicken is a yogurt or buttermilk marinade, because the mild acidity in the ingredients will help open the chicken for the rest of the flavors while also providing some moisture without the harshness of vinegar.
Fish that is prepared on the grill can easily be overcome by a strong marinade and can fall completely apart if it is too moist or heavy with the liquid. A marinade for fish should not have an overpowering taste and should be balanced, because the flavors will be much more pronounced as a result of the short cooking times and delicate taste of the flesh. An Asian barbecue marinade is ideal for fish, because it will be balanced between sweet, salty, sour and savory. In general, fish also should not be required to sit in a marinade for very long so it can retain some of its own flavor and texture.