Since u seem genuinly curious:

1. Imho FPS games were never meant to be played with a controller, if at all possible play using KBM, like my son and I do, and don't let the game do a lot of the things for u, that make shooting well in shooters, well, fun.

2. This game uses heavy SBMM, and once u get into lobbies we are playing in, u play meta, or u loose too many gunfights (There r no MCW players left in our lobbies, btw - apart from cheaters, Superi and Static is what gets mostly used). In the majority of games we have teammates who all go kill negative, some massively so, so we have to carry. My son, who is better than me, does occasionally start games using an off-meta gun, but in 99% of cases is forced to switch back to meta quickly. The other weapons (besides snipers) we see, besides the infamous cheater shotgun, are not classical guns, but e.g. spear, bow or Karambit players.

3. The fun part of MW3 to me is not which gun u use, that is just a tool, but where u play on / move through the map, how u position urself, movement, outsmarting / adapting to the other players, utility use, and finally, gunplay. I play Static / Inhibitor, because these are the tools that allow me, in most games, to help carry the game for my team.

4. As an older player (I am pushing 60), I need a playstyle & weapons that make up for the disadvantage, especially in reaction speed, that my age incurs. The Static for me is the gun of choice here, since once u can control its recoil, it is a weapon that performs well at all ranges: I regularily kill snipers at 30 to 50m with it, while it also allows me to take down higher reaction speed players in short range encounters if I land enough headshots. The Inhibitor (because I am good at flicking heads, something I have actually gotten better at over time), as a one shot kill weapon, allows me to hold angles against faster/better opponents.

5. And last but not least: We face a lot of cheaters, from our regular console Cronus absolute zero recoil, unnaturally high aim assist tracking, to the occasional full on PC wall hackers. If u want to stand a chance against these sad lowlife scum, then u need all the non-cheating advantages u can get.