Wow, that is a really loaded question. I've done a lot of both, and I'd have to say that if I was blindfolded, it would be hard for me to tell the difference if they both were done right. I guess the best analogy would be to take two chefs, one cooking with a conventional oven and one cooking with a convection oven, and then having them compete. The oven type isn't going to separate the two chefs, it's going to be their cooking skills.
They each have their advantages and disadvantages. While personally I prefer the taste of BBQ on a stick burner, I've mainly used charcoal and wood chunks lately because I'm getting lazy and don't want to tend a fire every 15 minutes. If you know what you are doing, you can produce good que on anything.