Pro: A wood handle provides a firm grip on your starter. This also can be used as fine and dry tinder. 98% pure magnesium is soft and easily able to scrape off for a HOT fire. High quality flint makes for the MOST RELIABE consistent spark.
Con: Must be practiced with. Once the basic technique is conquered you will be able to start a fire almost anywhere. Due to such high quality, the prices are a little more expensive.
Square Magnesium Block:
Pro: Light, compact. Comes with Magnesium and Flint some models come with small saw blade for scraper.
Con: No handle, which makes it slightly harder to hold onto when extremely cold and or wet. Magnesium is not in its purest form, and can be very hard to scrape off. making it useless. Flint is inconsistent and some what unreliable in ensuring you will start a fire.
Pro: Mostly likely will work when wet. Very easy to use, and contains 25-50 per box.
Con: Matches do not work in windy conditions. They also break easily in your back pack or during use. You will only have as many attempts to light the fire as you have matches, no more. Some fires take multiple tries.
Pro: Very easy to use. Works in moderate climates. Not expensive and easily replaced. Can also use spark for signal.
Con: Unreliable! Most likely will not work when wet, and does not light damp tinder easily . The less money you spend the less likely it will work for you when needed. Disposable. Butane gels in cold temperatures, and vaporizes in high elevations.