Actually, we love them both! There's no right answer, but one usually suits you better than the other.
If you like the natural approach, with charcoal as the main heat source and various woods to add flavor, it's tough to beat. It allows for lots of experimentation, and competitive barbecuers invariably use this method. Charcoal barbecues are simpler, and usually cheaper. The drawbacks — as anyone who has used one will tell you — are getting the thing lit, maintaining an even temperature, and cleaning up after.
You'll never have trouble lighting a gas barbecue grill, and it's far more controllable. Though it isn't necessarily easier to clean, there's no hot ash to get rid of after. For most people, it's the more convenient, easy-to-use option.
It's a personal decision. A barbecue is a great way to cook — and entertain — however you do it!