All depends on what you're cooking. A gas grill is nothing like an oven because you can't sear in an oven. The biggest advantage is better control the heat. High heat is there when you need it, gone when you don't. Foods that benefit from this include tender vegetables, breads/baked goods such as pizza, and stuff that needs high heat searing like streak, lamb, and pork chops. Imparting a smoky flavor doesn't really help these types of food.
Charcoal works well for things like burgers, ribs, chicken. Medium heat foods that don't have a lot of favour on their own. You'll see a lot of professional BBQ chefs use both types of grill for these reasons. Best of both worlds.