There are pros and cons to both gas and charcoal grills. Figure out what you need, what features you want and what you're willing to put up with to figure out which type is right for you.
Charcoal grills are usually much less expensive than gas grills.
Figure out how much total cooking area you need. The kind of food you grill and the number of people you're cooking for are important factors in choosing the size of the grill. Remember that the total cooking area listed on the sticker includes the warming rack if there is one. That means your actual cooking surface is smaller. Try to get wheeled barbecues of either variety.