Charcoal gives more flavor and is considered more authentic by "real" outdoor cooks. Gas is a hell of a lot more convenient, more temp control, and easier cleanup. But it won't give you smoke flavor unless you add a packet of wood chips to add some smoke.
If you use a charcoal grill, use lump hardwood. Much better smoke flavor. Briquettes have god-knows-what-chemicals in them. Do you really want your food cooked in a cloud of that stuff?
Same for lighter fluid--don't use it. Get a charcoal chimney instead. Super easy and will have your hardwood ready to cook with in just a few minutes.