At its core, The Division 2 is more of a RPG than a third person cover shooter. It may not seem like it at first, given the modern setting and heavy emphasis on firearms, but your gear and abilities (referred to as Skills in the game) arguably have as much of an impact on your performance in combat as your ability to click heads. As such, it's important to equip the right Skills for the right situations. With so many Skills to unlock, it can be hard to decide which is the "best." To help you decide, here is a brief overview of the most universally useful and the most niche Skills.
It should be noted that as you advance through the endgame world stages, enemy health and damage scales up drastically. Some of the Skills, especially the DPS related ones like the Turret, slowly lose their effectiveness as a result. Fortunately, the status effects that Skills apply aren't really affected by enemy health. Healing and utility Skills generally scale better and remain relatively effective at the endgame. It should also be noted that Skill power bonuses and mods appear to be drastically underpowered, making some Skills feel particularly terrible at endgame.
Division 2 Most Useful Skills
Chem Launcher - Healing
On paper, the healing variant of the Chem Launcher seems underwhelming. It has a tiny area of effect and it doesn't have the raw healing output of other healing Skills. In practice, however, the Chem Launcher's healing capabilities should make it a priority unlock for most players. For starters, it can't be interrupted easily. Enemies can shoot at the healing Drone or Hive and destroy them. Enemies can't really interact with the healing field of the Chem Launcher once it's deployed.
In addition, even though the Chem Launcher only heals about half of your armor bar per use, you have three charges that have their own individual cooldowns. Furthermore, the effects of each individual charge stacks, so you can quickly recover an entire bar of armor in a couple of seconds and still have another healing charge for immediate use. It is, bar none, the quickest and most consistent source of healing in the game.
Hive - Reviver
The ability to completely undo a death is extremely powerful in any game, and this is no different in The Division 2. The Reviver Hive simply makes it so that if you're playing solo, you basically have two lives. If you're playing with a group, you won't have to risk leaving cover to revive someone. Of course, one can argue that it would be more effective to equip a Skill that actually does something 99% of the time to prevent dying to begin with.
Turret - Any
Seeing as how you're generally going to be outnumbered in The Division 2, it might be a good idea to bring something along that can watch your back for you. As one may expect, the Turret offers automated gunfire in a variety of flavors. All of them are equally potent at their intended role, with the only downside being that you can only equip one variant at a time. If you really can't make up your mind, the standard Turret is always a solid choice for every scenario while the flamethrower Turret offers extreme close range crowd control and damage. Simple, easy to use, and effective, the best traits that you can ask for in a Skill.
If you pick the Demolitionist specialization, you gain access to an Artillery Turret. It basically fires grenades at an area of your choice. The downside is that the Artillery Turret has a long cooldown and it has limited ammo per use. It's also somewhat awkward to aim. On the bright side, it combines AOE damage, status effects, and giant explosions into one package.
Seeker Mine - Explosive or Cluster
What's better than a grenade? How about a grenade that guides itself to a target and causes it to panic before being blown to smithereens. Even if the Seeker Mine is destroyed before it reaches its target, it will fulfill its role of removing an enemy from the fight. The only difference being that a successful Seeker Mine detonation tends to accomplish this task in a more permanent manner. Unfortunately, Tanks (the massive armored enemies) don't really seem to care about the Seeker Mine. Another example of an easy to use but effective Skill that doesn't have any glaring downsides. You may want to use something else if you're looking for raw, instant damage at high world tiers though.
Divison 2 Niche Skills
The Pulse Scan Skill reveals the exact location of every enemy within a small radius. That's pretty much the extent of all that it does. There's no noticeable buff for attacking marked enemies. While it is true that being able to tell exactly where an enemy is is a powerful weapon in its own right, enemies in The Division 2 don't really hide their presence well. The EMP variant of the Pulse Scan is marginally more useful, but unless you're constantly going Rogue in the Dark Zone, there's little practical use for a short range disruption ability. That being said, the EMP would be quite effective against the Black Tusk faction, if you can get close enough without being shredded.
With how chaotic the battlefield can be, it would be safe to assume that you would want the most idiot proof gear possible. The Firefly takes this concept and turns it completely around. Every variant of the Firefly requires you to manually mark a target for the tiny drone to do something. That in itself isn't a problem per se. The problem lays in the fact that the Firefly has some rather demanding proc conditions.
Want to do massive single target damage? Great, except you can only target armor plates, weak points, and exploding red barrels. Want to do AOE damage? You have to mark two targets, and then those targets have to get close to each other to detonate. Considering how rare it is for The Division 2's AI to huddle together outside of spawn doors, you would be better off just throwing a grenade. On the bright side, the Blinder variant is quite good at crowd control and should not be overlooked.
Drone - Defender
The Drone is one of the more jack of all trades Skill branches, offering a bit of everything but not really excelling at anything in particular. However, the Drone does have a unique variant that makes you practically invulnerable to bullets for a few seconds. At high world tiers, the couple of seconds of invulnerability can be invaluable. The abundance of cover does make this variant of the Drone somewhat redundant though.
As its name implies, every variant of the Ballistic Shield gives your character a bulletproof riot shield. Using the shield prevents you from using most weapons. It can be assumed that Massive intended to have the Shield act as a generic Taunt/Tank ability in The Division 2. That is the theory behind the Shield's existence anyways. In practice, while the person using the shield may be safe from gunfire, the corresponding loss in DPS is going to make everyone else less than pleased. This is doubly true with the new armor mechanic which emphasizes coordinated, precise gunfire on a single target. Throw in the fact that Skill Power scaling appears to be absolutely broken, thus preventing most people from boosting the Shield's health, and you would be hard pressed to find a more niche Skill.
What skills have you found to be the most useful in The Division 2? Let us know in the comments below!