MiniMe has done a good rundown, but I have a couple of other points.

My expensive piezo-electric butane lighters commonly do not ignite at high altitude. The fuel/air mixture seems to be incorrect. Spark wheel butanes do work for me at altitude.

My Zippo has real cotton wadding. I confirmed this by removing a small portion and igniting with a spark rod. It burned completely with the odour of wood not melting plastic or unburnable glass wool etc. The residue was consistant with cotton, dark brown ash.

I think cheap butanes are a great thing to spread through your gear, while you keep your Zippo for everyday use.

I do not smoke, so my Zippo needs topping every week.....an easy thing to forget, but it is essentially useful empty where a high end butane is not.

I avoid the high price piezo electrics as I am at high altitude often enough for this to be a problem.

I carry, Swedish firesteel and cotton/vaseline tinder, Silva matchcase with strikeanywheres, and a saran wrapped Zippo On-body. Additionally I have a small flint butane in my PSK, stove kit, etc and other BSA rods.