yeah thats what im doin now, got all my AR's and SMG's done, Just working on the AA12, model and
The XM-25 is absolute trash. If I was a noob and absolutely just couldn't aim a weapon I guess I'd consider it but seeing as it has such poor damage I just can't rationalize using it.
The Riot Shield is also pretty terrible until you get Speed or Melee unlocked on it.
The Model 1887 looks cool but until you get Damage on it it's just too damn slow on reload if you don't kill someone in 1 shot.
All the SMG's are pretty good for running around and getting kills with. All of them take very well to rapid fire and silencer/extended mags. The PM-9 is probably the most difficult to use of the bunch seeing as it has so much recoil, low damage, and eats through bullets so quickly. However, I love running it with Scavenger Pro, Quickdraw Pro, and Steady Aim Pro, with endless bullets and the ability to fire from the hip it's actually not a bad gun. You don't need to use Rapid Fire on the PM-9 because it's already capable of putting out a lot of bullets, and the range on it sucks so I don't think I'd use Silencer either. I usually go with Melee and Extended Mags and try to get in plenty of close quarter situations, it's pretty hard to lose with a PM-9 if you're close enough.
As far as the best heavy gun in the game goes I'd have to say the L86 LSW + Silencer + Thermal Scope, hands down. The Thermal makes the gun have almost no kick and you'll get a Pave Low almost every time you use it so long as you're on a decent team. If you don't want to run Thermal the gun is still amazing with Iron sights. It probably has the best Iron Sight of any LMG in the game. I like running Scavenger Pro, Hardline Pro, and Marksman Pro with Silencer + Extended Mags. You start out with 3 clips of 150 bullets and you'll basically never run out of ammo. Just don't try sprinting around like a chicken with your head cut off as you would with an SMG because the draw time is a little slow. If you run Specialist and have Quickdraw as your first Perk that would take care of that though.
All the AR's are good. I feel like the M4A1 doesn't get near the credit it deserves. I run it with Silencer + Extended Mags and get 2-3 Escort Airdrops a game and usually go something like 35-15 just running around all over the place with it. Of course that's running Hardline Pro and throwing plenty of grenades while I'm at it so I can get some extra Assists to Count as Kills.