Keep in mind that those two brands are big box, kinda low end products. You will pay much more for a grill from a specialty store. Will it cook better? Maybe. Is there a point of diminishing return? Absolutely. I used to think Weber was so great. But upon close inspection of models from various manufacturers I am seeing that there is not much difference between similarly priced grills. I have had two Weber's and one Kenmore, and my son has a newer Char-Broil. If I was in the market for a moderately priced grill, I'd look really hard at the Char-broil that my son has.
As far as using charcoal, ask the ones touting how great it is how often they use it. Ask them if they cook with it when it's sub-freezing outdoors. Then ask yourself what kind of griller are you going to be. Are you looking to cook up some really tasty meals on the weekends and other occasions? If so, I would go charcoal.
But if you are going to use it 5-6X per week year round then go gas. Yes, it won't taste as good. Yes, it is basically baking outdoors. But if you like the food you cook in your over but would rather take it outside for whatever reason, you won't be disappointed with gas.
