Definitely the An-94. Was nerfed quite a few times considering how powerful it was. It does more damage overall and gets the first 2 bullets off faster. The MTAR, on the other hand, I believe has less recoil. I'd use stock (move faster when aiming) and quickdraw handle (aim down sights faster) on both. Also pair them with lightweight, toughness, scavenger, dexterity, and extreme conditioning. Both are great but most people would pick the An-94 over it.
Honestly, when I look at the Time to Kill for both, the are the same if you just full on hose at people. And because the MTAR is lot easier to handle, plus its pretty much the same in most ways, I'm gonna go with the MTAR here.
GT: SouL C Mo Still making montages for Conduit 2. Somehow. lol
I use to prefer the AN94 in the very beginning before the nerf. One of the biggest properties that alot of people didn't know about was that it gave others flinch. That might not matter to many, but when you both draw your gun and shoot at the same time, the other person would miss more because of that feature even if you had the toughness perk. After the nerf it just does like the SCAR except a bullet faster after every pull.
I'm not good at hitting targets with the first 2 bullets so this gun isn't for me. MTAR once you apply certain attachments seem to shoot like a laser. I feel more comfortable with it as well.
One thing for some is if you have a modded controller with rapid fire and place it on lower settings, you could definitely be over powered with the AN94, always rapid firing the 2nd bullet and having zero recoil on top of that would be cheap.