I like aspen for the same reasons: I like the look of it and it's really easy to spot clean. A lighter bedding is going to show up poop/spilt water/mold much better than a darker bedding, so you can be certain your snakes are always in a clean environment. Plus, I feel like it gives my snakes something to do -- its lightweight & fluffy-like so they can push it around to how they like it, or spend the day flattening it out like some do, or burrow underneath. Also, it makes my Provent-A-Mite process much easier.
I do not know why your bedding smelled bad... all I can think of is retained humidity that might make it sticnk (maybe more air holes in the tubs?). The only time mine ever smell is because of reasons for it to smell -- dead mouse smell from recent kill, poop, spilt water getting icky under the bedding, etc...
One reason I don't like it is that it is DUSTY. When I do full cleanings from transferring old bedding to the trash can and new bedding from the container, after a while the dust in the air from inhaling it and stuff really gets to me. But this is not a regular occurrence, this is just from major messing around. Hope this helps 
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Cheers!
• Chelsea Lynn Gardiner
(and Frank M. Wood)