My favorite gun switches between the Galil and the Famas. Really, it depends on the day. In either case, though, the iron sights are really solid, so it depends on which mode I'm playing when it comes to my attachment.
If I'm playing hardcore, I'll use a Silencer. Also, I try to stay off of any radar they may put up, so I'll use these perks:
Perk 1: Ghost (Pro). For obvious reasons.
Perk 2: Sleight of Hand. I don't like my chances of staying alive while reloading.
Perk 3: Hacker Pro. Keeps you off the motion sensors and helps avoid claymore deaths.
In core, I find the Silencer to be more of a hindrance. So, to get some 'extra perks' out of my attachment, I go with the Dual Mag. Also, I go with these perks:
Perk 1: Hardline. Get those killstreaks early. I'd also run Scavenger, but that's why I've got the Dual Mag.
Perk 2: Hardened (Pro). Objects do less as cover, and if you've got the Pro version, it'll reduce your flinch by 75% (or something like). Again, the Dual Mag covers SoH, at least, in my estimation.
Perk 3: Hacker Pro. For the same reasons as above. I like Tactical Mask or Ninja equally well here, though.
I hope that made sense . . .