"Funnest" or "Most Fun?"

Photo Credit.
I've got a question: is "funnest" a word? According to the dictionary it isn't, but it seems to be a logical construction to refer to something that is the most fun. I ran into this problem today as I wrote the intro to a short blog post over on Greg Rides Trails.

The line in question reads: "I rode one of the funnest downhills of my life yesterday... and it was here in North Georgia!" I tried changing it to "most fun," which might technically be more grammatical, but it makes the sentence quite awkward: "I rode one of the most fun downhills of my life yesterday... and it was here in North Georgia!" In addition to the adjective "fun," which is rather ambiguous, I considering using the word "epic" but rejected it because of how often that word is used. 

The best solution to the problem may have been to just re-word the entire sentence, but I honestly just didn't want to do it. While not the most inspiring first sentence in the world, it (and the other couple of introductory sentences) does its job: try to hook the reader and introduce the photos below at the same time.  

I think the hook in this sentence comes from the surprise at the end: that this downhill which had been "one of the funnest" was located in North Georgia.  

All told, I think this was an effective sentence, but the question of "funnest" VS. "most fun" is intriguing. 

What say you: does it depend on the situation, or is one word/phrase correct and the other incorrect?