What game mode and classes are good for getting a good kill death in modern warfare three

For me the best Game Mode is Team Defender, or Domination. The Best guns for lower levels are PP90M1 if you in level 30, while you use the PP90M1 you'll unlock the ACR 6.8 at level 50


PP90M1:
The PP90M1 SMG is a new addition to the Call of Duty Series. Developed in Russia, it is a helical variant of the AK74u. This weapon was designed by the KBP Instrument Design Bureau in the 1990's. In case you didn't know, a helical magazine extends the drum magazine design so that rounds follow a spiral path. This allows a large ammunition capacity in a small compact package.
ACR 6.8:
The ACR 6.8 will be returning in MW3. Many Call of Duty fans will remember how accurate the ACR 6.8 Assault Rifle was in MW2; as it had virtually zero recoil. This gun was designed by Magpul industries in the United States. The ACR 6.8 can be unlocked at Level 50.