The real reason to buy a charcoal grill is that charcoal can get hotter than standard gas grills, and heat is what you need to get steaks and lamb crisp on the outside and red or pink on the inside. Charcoal grills typically cook up to 500F. If you use a lot of coals or if the coals are raised close to the cooking surface, they can cook as hot as 700F.
On the down side: Charcoal is dirty to handle; it can be hard to light; it takes about 15 minutes longer to get up to temp; there can be flare-ups that can burn the food and that is a health risk; it is hard to tell what temp you are cooking at; the temperature cannot be turned down rapidly; during long cooks it slowly loses heat and you need to add more charcoal; charcoal grills rarely have rotisseries; and there is a lot of ash to clean up after.
The choice doesn’t get any easier.