Kanthal, it is the most used wire and most common on all the coils in the market and it can be used on a regular device on regular power or volts mode.
Nickel (NI200) wire, it's a very low resistance wire and it's resistance varies when you apply current on it making possible to some devices to control temperature just reading those resistance variations and making calculations. This wire CANNOT be used on regular power mode because of it's fumes provenient to the Nickel degradation and that's bad to inhale.
Nichrome 80 is another wire type that gained popularity with vapers to use for their RBA coil builds. Although a lot of vapers still swear by it, slowly kanthal is starting to take its place. Nichrome 80 is an alloy of nickel and chromium, it is composed of 80% nickel and 20% chromium.
Compared to kanthal wire, nichrome is much less heat resistant at 2462 degrees Fahrenheit, but it heats up much quicker than kanthal. Because it heats up much faster, nichrome 80 is very popular among sub-ohm cloud chasing vapers.
Titanium Wire, works pretty much like the previous one, but it gives you higher resistance then NI200, better ramp up or quick heat and quick cool down, and just like NI200 this wire CANNOT be used on regular power mode because of possible formation of Titanium Dioxide and that's bad to inhale.
Stainless Steel Wire, on the other hand, can and should be used just as kanthal on regular power mode devices, but with the advantage that it can also be used on temperature control mode on devices that have that function. You can still use it on Titanium temperature control mode on most devices out now but you need to start on the minimum temperature like 200ºF (100ºC) because the Stainless Steel Wire Temperature Coefficient is low compared to Titanium the temperatures will be that off. Me and also other reviewers and vapers agree that the flavor coming from the vapor produced on a coil with this wire, tastes more clean and crispy.
To conclude, Kanthal has a higher Max Operating Temperature which will give it a longer life on your RDA. Nichrome heats up at a faster rate and is sometimes preferred for this reason for "cloud chasing" or sub-ohm builds. Some people taste a difference between Kanthal and Nichrome stating a more metallic taste from the Iron in Kanthal. It depends on your personal sensitivity to metals, and what you like. It is all subjective and really comes down to what you personally like!