CoD 4: M16A4 + MP5

CoD 5: MP40

CoD 6: UMP .45, Model 1888, G18

CoD 7: AK74u

CoD 8: Type 95, MP7, FMG9, Striker, ACR 6.8

The point is there are always guns that people use more than others because they are the best in their class, think about weapon balance in MW3, what's the over-powered gun? I can think of at least 10 off the top of my head. 

If it's better than the gun you're using, switch to it and show all the other players that you're better than them. I don't understand why people feel like they have to play using one of the worst guns in the game, some sort of attempt to inflate their e-peen I guess? And then they come on here and complain when their skills are not good enough to overcome the handicap they've willingly chosen to give themselves.

It's almost like a sniper complaining about not getting one-shot kills when he's using a silenced RSASS on core. You know what the guns in the game are capable of, it's your choice. Personally, if I saw a guy dominating match after match using one of the "OP" guns, I wouldn't think "What a noob, using that stupid ACR, ect." Instead I'd be like "Yeah, that guy's pretty good." Point being, if you're good you're good. Putting an MP7 into a bad player's hands doesn't somehow transform him into a beast. They'll still suck. Most people play this game to try to be the best (rather than trying to prove a point), so it only makes sense that they'll be equipping what they feel are the best guns in the game.

People have there favorites.  Whats the problem with that?

My favorite weapons is the CM901 and Mk-14

The weapon I use to HELP MY TEAM WIN THE GAME is the ACR.

...

I feel an obligation to work with my team, because I'm not playing alone and other players on my team are lose out on the experience when I don't successfully protect their backs.

WHEN people are bad, or use bad weapons, they make the game less fun for their teammates AND themselves.

IF weapons were better balanced, people would use more weapons without causing frustration within their team.

Really.
Why do people WANT some weapons to be bad?

"Hard to use" is fine.
Because that means that using the weapons is a "challenge of skill" -- unlike using an underpowered weapon which is a "battle uphill".

Take a high recoil weapon semi-automatic weapon with high damage for example.

To kill an ACR user, you must fire accurately and manually pull down the sight for the second shot, or die.

A challenge of skill.

Then take a weapon with low rate of fire and the same damage as the ACR with higher recoil.
To kill an ACR user, HE MUST MISS ME while I must hit him. I need for him to make mistakes for me to win.
A battle uphill.

Because otherwise the game would be no fun