Which is the best (newish) CoD game?

I admit, I have never ever played a Call of Duty game in my life and now that there's a weekend sale for pretty much all of them on Steam, I'm tempted to try one out. I would prefer it to be relatively newish so can anyone please tell me which of the CoD games is "the best".

Now, by "the best" I this case I mean an enjoyable multiplayer experience serving enough fun to keep me playing for a while. Which one is it? Ghosts? MW2? MW3? Black-ops? Black-ops 2? MW Black-ops? Black ghost ops? ;) Let me know what you think.

Well, the last one I played properly was 7, Black Ops. I quite enjoyed it, really. Then again, that was a fair time ago, and it was on PS3. Stay away from Ghosts.

My personal favorite was the OG Modern Warfare, that being said I have never played it on PC so I can not comment on how good it was there. I have high hopes for the new Advanced Warfare and if I were you I'd just hold out until then because everyone will have the same skill level with it and you won't just get owned by seasoned vets. 

basically every call of duty before modern warfare 3. but black ops 2 was quite good at some point but got stale later on. 

If you get motion sickness/simulation sickness from low field of view (we're talking 55 or 65 on a 16:9 monitor), stay away from the newer CoD games made by Infinity Ward (MW2, MW3, Ghosts). I hear CoD4: Modern Warfare is decent, though.

CoD4 and MW2 were my prime games when I was in middle school.