If you could only pick one weapon...

Probabl ythe Locust it's a fas t firin gweapon with really good accuracy an ddoes a decent amount of damage for an SMG

Gah cannot remember what good guns were in ME3... maybe there was something but I liked Adept more than guns.

From MEA I'd bring Dhan immediately. Thats the end of enemies in mid range.

Obviously depends on the class/build, but generally for ME3 it would probably be the Claymore. I have used it on all classes at some point. Really good with the Infiltrator and Vanguard obviously. Adept and Sentinel do not really need guns when bringing Liara and Javik along most missions, so the Claymore would just be a bonus. Soldier has to be more strategic with it, but I have done before and it was fun. Engineer would suffer from the cooldown penalty the most, but I have done it with the Engineer as well with some builds.

For Mass Effect 1, definitely the Spectre Assault Rifle assuming the class automatically gets the Assault Rifle talent to compensate, or just the Spectre Pistol since everyone can use it anyway.

No idea for Mass Effect 2. The game mechanics kind of require you to use at least two guns for most classes.

Mass Effect Andromeda: Probably the Dhan shotgun?

Arc Pistol if we're talking effectiveness.

Used correctly, it's a rapid fire Black Widow with a much bigger magazine and 200% PRS on almost any build. Totally broken. Heavy barrel and big magazine with AP ammo

For fun, an incendiary explosive equipped Claymoar gets the vote. Smart choke and HVB (change one for Omni blade if you're brave/Krogan)

BOOOM, Muahaha they're dead

I know, right?
I was absolutely certain RedCaesar97 and Hanako Ikezawa would post (and I was right) but where are the others?
XD

Wait I remember having N7 Valkyrie in ME3 too.. just had a flashback to Omega DLC (yeah cant remember the name) thats a good one in it too, like in Andromeda, but in Andromeda one can craft it a bit OP
(You'll need that on insanity, the rush is sometimes harder than on MP Platinum!)

It's been a while but IIRC, I found the Harrier to be massively OP in ME3. So if I just wanted to rule the battlefield, this would be the gun for me.

Graal spike thrower. Imagine how horrible it is to see your buddy shot. Now imagine, instead of a bullet, he got hit with half a dozen eight inch long razor sharp harpoons.

If it didn't suck absolute ass I would have said the Firestorm for the same reason.

No matter how good or bad it gets, I'm Mattock trash through and through.

Hey, the Mattock isn't trash, it's a classic.

If I remember right, it's based off of an older design philosophy.
The kicker being that it's EDI who thought of it.
"When an AI criticizes you for for being too 'high-tech', it gives you pause to consider."

*bows* thank you