In my opinion, almost everything is better when cooked on a grill outdoors. I tend to prefer a charcoal or wood fire, although gas is good also, because it can be very convenient. When the fat drips down, it stokes the fire, which gives the food a nice flame broiled flavor.
I've never cooked much seafood on the grill, other than shrimp in kebabs, so I don't know whether I'd prefer it on the grill, but other than that, I do grill a lot of meat and vegetables, and they're fairly quick and easy to cook on the grill, as well as not heating up the house, which is nice in the warmer weather.
I'm a fan of street grilled dishes. Whenever possible, I always replace cooking on the stove with grilling...
And I'm sure that a burger with a patty or small pieces of meat that were cooked on the grill will be tastier than the standard one.
Guys, are you making your own burgers or frozen bought ones?
I love burgers cooked over the coals, but... I'd be lying if I said I didn't prefer a burger cooked on a flat top. There's some kind of magic that happens when a burger is frying in its own fat and juices.