The arena in my barn currently uses hog fuel (wood chips/shavings) in the arena, and I have to say that I am not a fan. The type we have is a mix of big chunks of wood, smaller chunks, shavings, and dirt. Over time the a lot of the wood has degraded and broken down, making it very dusty. We have a sprinkler system, but if you wet the footing down enough to significantly control the dust then the hog fuel/dust/ mixture becomes muddy and very slippery. If there's one thing I hate, it's horses slipping and losing their footing, so most of the time I just won't water the arena. I figure dust is better than my horse slipping and going down. I also sometimes find wood chips wedged in my horses' feet after I ride.
My trainer agrees with me, and isn't a fan of the hog fuel in my barn. However, she says that if you get the right kind (smaller chips) and properly maintain it (water and drag every day), it is a good surface to ride in.
My favorite footing is not-too-deep sand. Of course, the to find your ideal footing you have to factor in what exactly you are going to be doing in it :-). Each footing provides a different level of cushioning, traction, and resistance. When I was playing polo I hated sand arenas, because it's hard to hit the ball in them. Now that I ride dressage and jump I love sand.