Alienation contains quite a few different weapon classes and types with their own individual variants. I know you are likely thinking, cut the crap and tell me which one is best. For the tank I liked the SMG and the Xeno Rifle worked quite well when using the Bio Specialist, but it really does depend on a lot of things. You will need to determine what your play style is and what enemies you are facing. The weapon you use should depend heavily on these 2 things. I will go into some detail below that should help you get an overview of them all.
When you play, you will have 3 different weapons to choose from. You can tap to switch between your primary and secondary weapon. You can then hold down the same button to equip your heavy weapon.
You will find that you spend most of your time using your primary weapon. It is typically the most versatile weapon, with the best balance between clip size, reload, fire rate and damage. Unless you have purchased all the DLC, you will find that each class has certain weapons it can use that other classes can not. I didn’t get much of an advantage out of using the DLC to allow other classes to use specific weapons. There isn’t much to know about the primary weapons, since you will find yourself sticking to the same type all the time.
This is where most of the decision making comes in. You have a few different types of weapons here. Your class, and the enemy you are against will play into this heavily. While using the tank, I found the shotgun to be the best weapon to use, regardless of the enemy. For the Bio Specialist and the Saboteur, the shotgun is good when you are against enemies that have no guns. In most cases, I preferred to use the pistol. For some reason the pistol weapons do a huge amount of damage, but they have a slow rate of fire. The powershot weapon can be useful at times, it seems to suit the Saboteur the best. This will let you deal large amounts of damage from a distance.
I spent quite a while playing this game and I really didn’t get much use out of the heavy weapons. You can choose from a rocket launcher, mini gun or a flamethrower. If you get the DLC you can get a weapon called the Collapser, which i found to be the only heavy weapon of use. It is handy to have a rocket launcher for crowd control when there are large groups of enemies grouped together and the minigun is good when there are just a lot of enemies. I never found much use for the flamethrower.
The grenade will be come one of your most valued weapons. Mines are also a type of grenade, but I really disliked this weapon type, even though it was one of the most powerful. The remote grenade is fairly simple, throw it and then press the same button to detonate. The remote grenade is the best, but the cluster grenade can also be good at times. If you get the season pass, you will get a grenade called the Vortex Grenade. This grenade is the best grenade in the game and is definitely the best weapon to have on the harder difficulties. It will suck up all enemies into a vortex, giving you valuable time to run away.
Each of the 4 weapon types above can come in a legendary form. Legendary weapons are the most powerful types of each weapon category. You can always identify a legendary weapon due to it being a bright orange/gold color when dropped. You will also get a trophy for the first one you collect!