For me, the important part of the backup isn't WHAT but WHERE. Namely, somewhere else, not in my cooking set-up. Typically, I've got two mini-Bics. One with my cook kit. The other with repair / first-aid stuff that really gets taken out. I have trouble imagining starting pine needles or wax paper with a piezo.*
I use a built-in piezo to light the barbecue at home for the first year. Then it dies (that's 50-100 uses) and then I install a new one or revert to a long-handled butane lighter.
*Always remember that your canister makes excellent tinder. By way of example: on a ocean beach in Alaska, I went in first in my sea kayak and got lucky. I made it through 5-foot breakers we didn't see from oceanside. I tried to wave my wife off, but she was already coming in and got dumped on just as she was trying to get out of her boat. I wanted a fire fast for her, so I dug a quick trench for my stove, lit my canister stove, put driftwood over the stove until the driftwood was going nicely, and then reached in and removed the stove. The was a big warming fire real quick that way.