it's a little hard for me to choose between crunching leaves under feet or popping bubble wraps. The only reason i would choose one over the other is availability and impact; one is seasonal which makes it more special since you can only enjoy it for a short time of the year but you can't beat the sound of popping bubble wraps. Have you tried wringing a whole sheet of bubble wrap and enjoying the continuous popping sound? it's a darn good stress reliever and it's addictive!!! I like both but if i must choose i would have to go with Popping Bubble Wrap.
There's even Bubble Wrap Appreciation Day which is celebrated on the last Monday of January. Have yourself some great bubble fun.