There are a lot of lists out there about all the exotic guns you need to have in Destiny 2, but you can only equip a single exotic at a time. It is just as important to be able to put together a solid loadout, with or without exotics. There are so many ways to do this I can't possibly cover them all. What I can do, is tell you all about the most utilitarian weapons I have found, and how they compliment each other, in both PvP and PvE. You'll find a mix of exotics and lengendaries here, and the list may expand with expansions. 

Nameless Midnight

A solid vanguard scout rifle with good impact and average range. The average range is compensated with explosive rounds. While the impact damage may fall off the AoE damage does NOT fall off. Staggers like MIDA but instead stops whole groups. Couple it with your Hunter while wearing Knucklehead Radar, and you have an explosive scout rifle that retains the ability to keep the radar active while you shoot.

Nameless Midnight is given as an option for every character to take at the end of the campaign. After completing the Milestone for completing 2 Strikes, Zavala offers it alongside Origin Story and Showrunner and while Origin Story is also a solid choice, Nameless Midnight is always my choice. Save your energy weapon slot for an assault rifle.

Riskrunner

Really an artisanal gun. A pretty solid SMG, Riskrunner REALLY stands out when you know you are going to be taking arc damage, making it extremely useful against the Fallen. But because MIDA Mini-tool is arguably the more well rounded gun, Riskrunner should really be used in specialist situations.

Hardlight

Really hard to not praise this assault rifle. Aside from the fact that it has no damage fall off, penetrating and ricocheting rounds, it also sports an entirely unique trait that allows its elemental damage to be changed FREE OF COST, making it my go-to weapon in literally any PvE encounter. The utilitarian's tool.

It Stared Back

A hard find, but one worth working for, It Stared Back is the Raid sword. A non-participant in OG Destiny's sword craze, I was super reluctant to use any swords in D2. It Stared Back converted me instantly. Sporting a fresh trait that puts heavy ammo back in your reserves for consecutive hits, it can SHRED a couple majors, or a swath of smaller adds.

Swords also have terrific PvP compatibility. Because the user is jumped back to 3rd Person perspective, using a sword in PvP allows you to peek around corners and strike with extreme lethality. Give it a shot if you haven't already, you won't be disappointed.

First In, Last Out

With the sad, sad departure of The Chaperone, FILO is a as good a replacement as you're gonna get. Add to that a trait that auto-reloads a portion of the magazine when critically wounded and you can deal high precision damage at close range that can bring most baddies to their knees. Best for PvP use.

MIDA Mini-tool

MIDA Mini-tool is the answer to the question, "What if MIDA had a little brother? What if MIDA had a smaller, more aggressive, bee sting of a brother?" Mini is an SMG with a firing rate that will bleed the shields off of even the most intimidating foes. It has solid PvP and PvE uses (despite the fact that I GET the business end of that deal more often than I give it), and when you equip it with its big brother you get a mobility boost that is nothing to shrug at.

MIDA Multi-tool

Look. What do I really have to say about MIDA Multi-tool. It is a workhorse. Good impact, good range, and a third-eye scope that keeps your radar active while looking downrange. You will see MIDA-multi on PARADE in multiplayer. Being able to see your enemies move while you pick them apart is invaluable.

The Number

The Number is my Hardlight when I have something else Exotic equipped. A Future War Cult weapon, if you didn't earn it during the faction rally you won't be able to earn it now, unfortunately. However, The Number is nearly interchangeable with Uriel's Gift and Martyr's Make. They are large mag, ricochet round, high firing rate ARs with stellar stability, The Number sports a trait that stiffens the last rounds in the mag for a little extra spice. Changing its damage type is not as easy as Hardlight. But it is worth keeping a couple copies if you get them.

Merciless

Need to melt a major? Or really anything with a gold health bar? Merciless is your AI infused Fusion Rifle. Where most Fusion rifles are STRONG, Merciless charges faster and faster until the enemy you are shooting dies. So pit this bad boy against a Beefer and you are going to be able to spit out the last 4 rounds of the magazine like it's a scout rifle. The effects are...extraordinary.

The Prospector

Grenade launchers are a new addition to the Destiny universe and in mob situations, they are seriously valuable. The Prospector is an Exotic grenade puking machine with full auto and trigger primed grenades, pull to fire, release to detonate. The heavy hitting grenades have great splash damage and in instances like the Raid Castellum, can mop up even the most intimidating groups. Don't be afraid to use it on a major either, the stagger alone will buy you and your fireteam time to breathe.

I hope this list helps offer a little insight into a few ways to experiment with your loadout. There are guns I still don't have, most notably Antiope-D (because the Gunsmith is a stingy bastard) so look for the list to expand, or for new lists altogether! Feel free to comment about your favorites at the bottom.

~Caleb
@LubWub