I personally loved the first 3 Call of duty games. I just tried the new CoD WWII today for a bit and think it was great. a more graphically detailed version of the old 1s. I will need to wait on new graphics being delivered before I actually spend time playing it. my 6Gb GTX titan died on me few weeks back and am currently running couple of old 2 ATi 6950 frozen III i had in 1 my old rigs and it can get a little laggy at times.
Call of Duty: Modern Warfare 2. Its not even up for debate, was the best COD ever created, I literally went an bought an XB1 just so I could backwards compatible the game and play my childhood again.