I used to think wood was the WTG, but gas is cleaner all the way around (pollution-wise), and you don't have to cut/buy/haul wood, and the wood doesn't have to be "seasoned". Then there's cleaning the ashes out of the FP, watching for "sap pops", etc.
The gas isn't as "fun" sometimes, but now that we have one, I can definitely see the allure...