This overview and comparison guide should help you to better understand the differences between the three tanking classes.which will help you get full preparation of WildStar release.
Engineer: Engineers use a resource called “Volatility” that builds up with use of their abilities or AMPs, and spends it to use more powerful threat and/or defensive abilities. They have access to many bots however only two can be used at one time, or you can choose to use none depending on your play-style. Your tanking Innate Mode: Provoke grants bonus health, resistance, and threat. On use it reduces damage taken, gains volatility, and puts on a EXO-SUIT.
Stalker: Stalkers use a resource called “Suit Power.” Suit power starts out at maximum and slowly regenerates over time. You have abilities to gain some suit power and many abilities to spend it. Your tanking innate Nano Skin: Evasive grants bonus deflect, resistance, and threat. On use you enter a stealth (currently a 25 second cooldown) that gives you access to several stealth only versions of some of your abilities. When exiting stealth Nano Skin: Evasive grants you 15% damage reduction.
Warrior: Warriors resource is called “Kinetic Energy.” Kinetic Energy builds up using abilities or AMPs. It decays over time as you stop using Kinetic Energy builders. Abilities do not spend or cost Kinetic Energy, however they require a threshold to be met to allow access to most abilities. Having a high amount or max Kinetic Energy allows for more powerful versions of most abilities.
Your tanking innate Stance: Juggernaut grants bonus maximum shield, resistance, and threat. On use it stops Kinetic Energy from decaying, and reduces damage taken. It also reduces your damage done, but brings up your threat to match. A tank specific ability, at max level, can reduce the cooldown of this innate.