Mine is the Shotgun. I love how reliable it is, especially in this game.
AR
Yeah definately shotgun for me 
Basically saved my skin time after time on the Library 
Shotgun and the 60 bullet AR! You can take out 3 grunts before reloading. The weapons more feel useful unlike the AR in Halo 3 and Reach (for campaign).
rockets and AR- rockets are -Yoink!- while AR is useful for once.
As I tighten the knot of my bandana firmly around my cranium, a subtle grin turns into the Joker’s smile as the sound of my Needler readies up.
(Some may say that the bandana is a Snake thing, but I know better.
John Spartan, the Demolition Man is also Rambo when he takes of his shirt and wears the bandana, and he never runs out of ammo.)
No bandana, I’ll take the SRS99 of course.
the carbine
Shotgun
The good ol’ Plasma Rifle.
I have 2.
The AR, this weapon will mow through grunts without a problem, and a full clip will take down a full shield elite. (343, please bring this weapon to reach)
The second is the shotgun, I know i couldn’t have survived the library without it.
The Sniper sounds and looks BEAST.Sniper.
Too many to pick! D:
- The pistol is just as amazing as it was 10 years ago
- The sound on the Sniper made my face do this the first time I fired it -> O_O I found myself wasting ammo afterward just to hear that awesome sound
- The shotgun, for obvious reasons
- The AR, because it makes a great backup weapon in this game!
- Needler. Need I say more?