As practitioners of logical thinking, I believe it is our obligation to take a public stand on contentious and important issues that fall within our expertise, even when it's unpopular to do so. So, I would consider it a dereliction of duty if I didn't state outright that Elf is a better Christmas film than It's a Wonderful Life.
Not only that, but Elf is the best Christmas film of all time and It's a Wonderful Life isn't even very good. It's a corny, overly sentimental, film starring an overrated actor who constantly chews the scenery. The film also had the odd and misguided aim "to combat a modern trend toward atheism." It was a box office flop that would have been (rightly) relegated to the dustbin of history had it not been picked up on the cheap for syndication decades later and played ad nauseum every Christmas until it seeped into people's brains and, I suspect, became inexorably intertwined with their fond memories of celebrating the holidays with family and friends. Now it has the power to induce warm fuzzy feelings in people when they see it and this feeling is mistaken for being evidence of profound art when, in reality, that feeling is just caused by nostalgia.
Elf, on the other hand, is the La Dolce Vita of Christmas movies. It is a work of pure genius, perfectly cast, and perfectly executed. No greater fish-out-of-water story has ever, or could ever, be told. It represents all that is good in humankind. It is the pinnacle of artistic achievement. In another 75 years, It's a Wonderful Life will be forgotten, while film students will be studying the mise en scène in Elf.