Depends on how you define 'best'.

Calling in an air strike works first time and every time. The only requirement is that you have friends with airplanes and ordinance, and some way of telling them when and where you want it.

On the other hand if I was tossing a fire source into a capsule set to be dug up in a thousand years a good size lens might be the way to go. Flint and steel, packed in wax, might be a close second. Both are light, compact and will last a long time and light many fires without wearing out.

Ferro rods are the basis for a lot of units. Ferro rods can, if exposed to moisture and salt, corrode away. The Doan's mag bars are even more prone to corroding away if exposed to moisture, salt, or in contact with dissimilar metals. But, of course, the risk has to be put into context. In normal use and a limited time , say five years, you may never see any sign of a problem. Wrapping them in wax paper or oil cloth, both of which make good tinder, largely eliminates the issue in the near term.

Blastmatch and similar are great, some can be operated one-handed, but they are mechanical devices and so subject to failure and they are not as small or compact as they might be.

All the spark based sources, lens, ferro rod, flint, depend on having dry tinder. Finding dry tinder in the rainy Pacific NW or the damp Southeast can be quite a challenge. Having to carry your own tinder and being dependent on it means the source of sparks and the tinder have to be viewed as a unit.

Simple and disposable Bic, Cricket or mini-Bic lighters are remarkably reliable. So much so that the armed forced, which used to demand waterproof matches in a match safe and/or ferro rods, allow the butane lighters as a substitute for either. Small, light, cheap, reliable and producing a relatively strong, hot flame without resort to fine, dry tinder they have a lot going for them. Which explains why they are the mainstay for fire lighting in a lot of groups.

When a forestry crew needs fire they often carry glorified road flares, called fusees, they are bulky, heavy and entirely one-time-only, expendable, they have their issues. But they are reliable self-contained units that are rugged and once lit they produce a very hot and relatively large flame that lights damp materials quickly. Once lit they are difficult, verging on impossible, to put out.

Ground troops use either a trip flare or a thermite grenade to guarantee a fire gets going. About one and two pounds respectively they are pretty heavy and bulky. They are also likely to raise eyebrows, and require some heavy duty 'splainin', if they are spotted during a routine traffic stop.

Matches are still a viable option. One you don't see as much of in the last quarter century. IMO the best, the gold standard for matches, are the genuine "Lifeboat matches" that are truly waterproof, burn strong even in wind, and come in their own protective vial that keeps them viable for decades. Strike-anywhere, blue tip kitchen and even the old-time, but often free, paper matches are lesser varieties but they are often good enough.

The weakness of matches are that they are to some extent vulnerable to moisture and they are single-use devices. On the other hand they are so light and compact that a half-dozen strike-anywhere matches dipped in shellac and tightly wrapped in wax paper and foil with a striker can be slipped into a pocket or two or the seam of a coat may some day save the day.

There are also the traditional woodcraft methods of using a fire bow, fire cord and fire plow. They work and perfecting the creation of, and use of, one of these devices is a worthy skill. The fire bow seems to be quickest, easiest and most efficient of these friction methods. Nothing quite so impresses people as collecting a few select sticks and using nothing but a knife and a boot lace to crate fire. Kids will idolize you. Hard core fire makers will dispense with the lace and manufacture their own cordage. Fanatic hard-core survivors will do it without the knife.

It is comforting to know that in a pinch you can produce fire with such primitive methods but they aren't always reliable. Damp materials, misting rain and fog can make the method difficult, verging on impossible. Pulling out a Bic or Zippo is far easier.

In the end the term 'best' depends on a lot of factors. How much weight are you willing to dedicate to lighting a fire. If your car camping a set of three fusees, are not to burdensome and you can use them as road flares. The same flares would be a real burden to an ultra-light backpacker. Air strikes and thermite grenades work for the US Army but aren't realistic for most civilians. Methods that are highly resistant to moisture and corrosion, or a really good method of preserving vulnerable devices, are going to be preferred for long-term storage, cashes, remote stocks. Cost, bulk, weight, ease of use, and ability to overcome difficulties like wind, rain and wet materials are values that vary in importance according to the situation.

My preference is for a couple of mini-Bics, one wrapped in wax paper and sealed in foil, and a ferro rod with steel striker attached is generally sufficient. In the remote area I might add a small match safe with lifeboat matches.

Many of my coats have small packets of matches stuffed in various places. making and using a fire bow, or a lens from the binoculars are both options. IMO carrying more than three, perhaps four in a very remote area, dedicated fire starting methods is counterproductive.