Kanthal and Nichrome (Ni80 or NiCr) are "resistance wires," that is they are intended to resist the passage of electric current and thereby make heat (I²R losses, if that means anything to you.) They are commonly used to manufacture electrically resistant heating elements in addition to vape coils; which latter are a form of electrically resistant heating element.
"Kanthal" is a proprietary brand name for a specific Iron-Chromium-Aluminum (FeCrAl) alloy. "Nichrome" or Ni80 are a generic term for a variety of Nickel-Chromium alloys. Kanthal is the granddaddy of vape coils, and probably still the most common wire. Some people, including me, can taste a slight metallic component on the flavor of juices vaporized with either type of wire.
Nickel (Ni200 or pure Nickel), Titanium (Ti) and Stainless Steel (Stainless grades are indicated by SSXXX where the Xs display the alloy viz. SS316) are Temperature Control or TC wires. This is because they exhibit what the cognoscenti call a "flat TCR curve." All metals conduct electricity. Some do this better than others, which is why copper is a better electric wire material than steel or aluminum. The ability to conduct electricity in all metals is affected by the temperature of the wire; the cooler, the less resistance. A "flat TCR curve" means the wire in question varies its ability to conduct in a very even manner versus temperature; a rise of X% temp increases resistance by Y%, and this stays constant or nearly so across the relevant set of temperatures. Because of this, it is very easy to build an electronic TC circuit, simply by measuring the voltage crossing the coil while it is firing. As voltage decreases during the puff, the temp of the wire is increasing by some amount, which can be determined by a calibration program. Thus, TC mods work by measuring this voltage and, the wire having arrived at the set temperature (voltage decrease), the mod then pulses the current applied to the coil, letting the coil cool a bit before applying more power, and so forth, to maintain the temp. Some circuit designs are better at this than others; generally you get what you pay for. Finally, Stainless had the additional benefit of being able to be used as a TC wire, or a resistance wire (TC mode versus Wattage mode on the mod).
Ni200 is about the worst wire I have ever used. I don't know anybody who uses it regularly. It only makes the list because it was the first wire used in the earliest TC circuits, before being replaced by Ti and SS. Ni tastes, and smells; it can only be wound in spaced (not contact) coils. Further it can make some nasty outgas chemicals if it is dry-burnt, meaning it is not safe to check the heating evenness of your coil before wicking and soaking with juice. If you really want to try some, I have a couple part-rolls I would be happy to donate, but I don't recommend it.
Ti wire I have very little experience with. Ni was so bad, I gave up TC and went back to strict wattage mode with Kanthal before it became available, and I did not try TC again until after Stainless was common. It is supposed to be very clean tasting, meaning you can't taste the wire at all. It is also expensive, like all titanium based products, and harder to wind in coils as wire size increases and coil diameter decreases; all of which follows from Ti being very hard and brittle if not annealed.
Stainless is simply the best vape wire I have yet found. I have a great deal of experience with it both in TC and wattage modes. I use it pretty much exclusively now. It has no flavor or smell I can detect and lasts a lot longer in the mod than Kanthal because it can be burnt clean (heated and scraped with a probe) every time you change wicks. I usually use wattage modes, despite my collection of TC mods, but probably because I started with mechs and am used to building coils to make the vape I want. I don't need no stinking circuit to control it for me
I also use SS wire in my mechs. I use it for everything.
Hope this helps.
