After a lot of hours of playing Call of Duty 4: Modern Warfare (around 600), I decided to share with everybody my ideal classes.
First of all, for those who are beginners, I am going to go through each class slot and explain what it's about. There are 5 types of weapons: assault rifles, SMG's (sub-machine guns , LMG's (light machine guns), shotguns and snipers. On each of them you can select 1 secondary weapon which is a pistol or handgun. Also, you can select one special grenade alongside with your frag grenade and then, it is time for you to choose 3 perks. For those who don't know what perks are, I am going to make a brief explanation. Perks are some kind of "packages" here in Cod4 which allow you to have a particular strategy. You will understand a lot more as I will start to explain why I choose the following classes.
In my opinion, you should have a class with every type of weapon. Let's get going!
Assault Class: The most efficient weapon in this category, in my opinion is the AK47 because it is very powerful, it has a medium to high fire rate and it is very good on a medium to long distance. Almost all the assault rifles are very good but each of them is good for a particular situation. I'm going to stick with AK47 on the most efficient assault class. Then I would suggest you USP.45 as your secondary weapon and a stun grenade as your special grenade. Now, the first perk should be either C4's or 3x frags. For the second one select stopping power. In this way, AK47 will be much more powerful and the enemy will die faster. On the final perk slot, you should take steady aim. This will allow you to shoot from the hip and hit the enemy quite easily. Now that you have your assault class set up, I would suggest you use it mostly in maps such as Crash, Crossfire, strike District and Backlot.
SMG Class: The most efficient weapon in this category is the MP5. Alongside AK47, MP5 is the best weapon in Cod4 if you ask me. I would suggest you get the Desert Eagle as the secondary weapon because it's very powerful and it contrasts with the lower damage of the smg comparing to the assault rifles. I would suggest you pick up a flash grenade because the SMG class it is better used in close field maps such as Chinatown, Overgrown, Pipeline, Wet Work, Downpour, Crash, District, Crossfire. As for perks, you should choose C4's or claymores, stopping power and steady aim.
LMG Class: All 3 LMG's are very equally balanced and I can't decide on one of them. It's your choice. All are very good. Select the Beretta M9 as secondary weapon and stun grenade as special grenade. As for perks, you should choose 3x special grenades, juggernaut mostly, if not stopping power, and steady aim or deep impact as you can shoot a lot through the walls with 100 bullets round.
Shotgun Class: In my opinion, the shotgun class is the rusher's class. Both shotguns are good depending on your preferences. If you have a good aim then choose W1200. If you don't have such a good aim as you would select the W1200, but you still are good at hitting with 2-4 shots, then select the M1014. As secondary weapon choose the Colt.45 and a smoke grenade as you can rush and plant the bomb in the bomb planting game-types. The perks should be: Bomb Squad as you need to know if there are any claymores or C4 on the enemy territory, sleight of hand to reload faster or UAV jammer so you can be undetectable on the enemy radar while their UAV is up and extreme conditioning so you can rush better than everybody and surprise the enemy.