"That will be adequate" - Gunther Hermann

"The Stealth Pistol" is the effective lethal alternative to the Tranquiliser Rifle, and usually consists of a silenced, laser-sighted pistol. As these mods are easy to get early on, and that the pistol can be aquired from the start of the game, most players will end up with this in their inventory.
Using the stealth pistol can cause problems, as some players (including me) find themselves dry on ammunition for the weapon in the final stages of the game. Reload speed and clip size upgrades are better suited for automatic weapons, but damage upgrades can be perfect for the tougher enemies in later areas.

"I was never properly trained in its operation." "Laugh it up, Denton." - JC Denton and Walton Simons.

"The Combat Shotgun" is easy to create if enough time is spent with the weapon. Every possible fire rate upgrade should be applied to this weapon, allowing as many rounds to hit the target as possible before the player has to take cover. This weapon is quite effective against bosses, and ((to an extent) robots. Since no silencer or laser sight upgrades can be applied, the shotgun is better-suited to loud and close playstyles, although it can fit in as a boss-killing weapon if no alternatives are worth carrying.

Ammo is easily avalible from most guards and gang members as well as in the enviroment, allowing players to fill up most of their inventory slots with ammo if they don't care about other weapons.

"The Combat Shotgun" is usually a fast-firing, high damage weapon with huge killing power at close range.

"Ask me, I think we should frag'em all. You trespass on UNATCO property, you get pumped full of lead." - Tech Sergeant Kaplan

The combat rifle is a strong weapon early on, but loses some of it's effectiveness after the first stages. For some players, the weapon becomes a use-it-and-lose-it weapon, being dropped when the magazine in emptied. If time is taken to upgrade the weapon, it can become a powerhouse against most enemies.
If time is taken to upgrade the damage and fire rate of the rifle, even armoured foes will crumble underneath the storm of bullets. Reload speed if useful for constant firing, but this shouldn't be a problem in most situations. Clip size has the same benefits of the reload speed upgrades, but with the added advantage of the larger amount of ammo you can carry (your inventory ammo plus the clip's ammo).

The laser sight upgrade is effective for any playstyle, but you must be sure that you aren't going to drop it in favor of another weapon later on. If you do, you have effectively destroyed the laser sight, of which there are only two or three in the game. The scilencer is only worth equipping if you are playing it stealthy, but the pistol is more effective for silent killing. Only attach this if you have a spare or aren't carrying a pistol.

Most enemies carry a combat rifle or combat rifle ammo, meaning that a constant supply should be avalible unless it is used for an over-the-top amount of time at once (such as attacking a boxguard).

"The Battle Rifle" is normally a quick-reloading and large-magazined weapon, unless all the possible upgrades are added, in which case it becomes a deadly mixture of everything hurt-related.

"What do you mean, almost?" - Bob Page

The machine pistol is usually considered to be the weakest weapon is Human Revolution due to it's common use by weaker-tier enemies. While it does do little damage to armoured enemies, the weapon can be upgraded into an easy support SMG with the right mods.
When choosing between fire rate and damage mods for this weapon, choose the fire rate. The damage upgrade adds about 10 damage to the weapon, but fire rate lowers the weapon's shot interval time by 0.1 seconds. Eventually, the machine pistol can reach the firing speed of the heavy rifle, while the damage will scale each shot up to 70. While this may seem powerful, the weapon is severely underpowered against ogres, heavies, bosses and robots with a slow fire rate.

If you are willing to pool all the possible upgrades into this weapon, it becomes a powerful rival for both types of rifle in the game, with ammo being carried by both gang members and spec-ops soldiers at many points in the game.

The only problem I personally have with this is that I never had the desire to fire the weapon, due to the fast rate it would deplete my ammo, despite having 450+ rounds in my inventory. I only used it during the final area of the game, and stopped using it at around 200 rounds.

"The Almost-SMG" is mainly an alternative heavy rifle, with high clip sizes and fast firing rates. Silencers and laser sights are, as you would expect, potentally wasted on this weapon if it's being used as a back-up

"You're right, a teacher would just love to have one of those things." - Adam Jensen

The heavy rifle suffers from three main downsides: low accuracy, loud noise and slow reload times. The noise is impossible to change, but accuracy and reloading are the two things that improve the weapon the most.

Reload mods are the key upgrades for this weapon, as you will be reloading very often and for a long time compared to other weapons. Fire rate is useful, but without the unique upgrade the weapon will just overheat faster, and the weapon does exceptional damage on it's own. Accuracy can be combated by simply attaching a laser sight, making the weapon a deadly torrent of pain.

Since a silencer cannot be attached to the weapon, all the enemies on the map will hear you fire the heavy rifle. Clip upgrades can help you during any firefights that trigger due to the noise, but once again can increase the chance of you accidentally overheating the weapon. Damage upgrades are useful for clearing the area before this happens, but can also make weaker targets seem like a waste of bullets.

"The Minigun" normally consists of a laser sight and reload upgrades, with a few damage upgrades throw in to increase killing power.

"A pistol is more than adequate. Hell, I dispatched a whole platoon one time with a pocket knife." - (General) Sam Carter

While the revolver is a powerful weapon in it's own right, it's worth upgrading it further into what I call "The Grenade Magnum". First off, get this weapon's unique upgrade as soon as possible, as this will add the "Grenade" to the weapon. While the upgrade isn't hard to find if you look for it, some players can go a full playthrough without spotting it once.
To aid your search for this upgrade, sometimes considered the best in the game, here's the three locations it appears at:
◾Detroit (second visit), purchasable from Grayson.
◾Hengsha, purchasable from Peng Xin Hao.
◾Hengsha (second visit), purchasable from Peng Xin Hao.

Once you have aquired this upgrade for your revolver, the next step will be to find a Laser Sight. When combined with Damage upgrades, the weapon will be extremely useful for taking down both Light and Heavy enemies. It also lowers the chances of hitting yourself during blind-fire from behind cover, and allows you to endlessly make an Ogre or Heavy stumble until he dies.

Since you cannot attach a Silencer to the weapon, stealth becomes a secondary tactic unless you are using the revolver as a backup weapon. Reload Speed and Clip Size upgrades are better suited to faster weapons, but can make the weapon slightly more effective if multiple are used.

Ammunition for the revolver is extremely uncommon until you meet Sandoval during the main storyline, after which it becomes much more abundant. However, most of it is present either in the enviroment or through vendors, as few enemies are armed with the weapon.

The bullets come out of the slim end, mate! - The Sniper

We all know of the vastly overpowered TF2 weapon that was made for the Human Revolution promotion. While we can't remake the weapon exactly, it can still be made into a killing machine.
COMING SOON

"My vision is augmented."
"That wasn't funny."
"Guess so." - JC Denton and Paul Denton

While most augmentations can be used in any playstyle, some should be considered before others depending on how you choose to fight (or avoid) any threats.

Stealth Pistol:
Since this combination of upgrades is usually used for long-range elimination, you need to be able to scout ahead. The Radar and Smart Vision augmentations both serve this purpose, but in different ways. The Radar - when upgraded - allows you to pick up enemy locations from a longer range without needing to visually locate them, helping you target your headshots from a longer range. The Smart Vision, meanwhile, gives you the ability to literally see enemy positions through walls. If you have enough spare Praxis to get both, they can aid you throughout the enitre game.

The Cloak System is also helpful, increasing your stealth abilities as well as allowing you to safely change position if a headshot goes wrong. It can also be used to sprint through tough crowds of enemies without being seen, which is useful if a large amount of enemies are about to investigate your position. However, this augmentation is probably unnecessary tosome players if total stealth isn't their playstyle.


Minigun / Combat Shotgun:
While most people would recommend Recoil Reduction, this is secondary to two of the most lethal augmentations possible - The Typhoon and The Reflex Booster. These two augmentations are useful for close-range fighting, allowing you to take down large amounts of enemies when the weapon magazines run dry. The Dermal Armour upgrades will protect you during prolonged fighting, making them really useful for charging into crowds of enemies and unleashing the other two augmentations.



Battle Rifle / Almost-SMG:
Nearly everything under the Arm Augmentation category is worth upgrading for these two weapons. Firstly, lots of ammunition is avalible for these guns, making the Carrying Capacity upgrades extremely useful. The Recoil Reduction isn't as useful if a laser sight is attached, but can still aid in your aiming when trying to hit a target at range. Punch Through Walls is the least useful augmentation in the tree, but can open alternative routes, and the noise can lure enemies away from their allies or a key area.