Also, I hear a lot about the engine and the graphics and what not, so being a programer and really paying attention to this stuff lemme recap.
Cod 4 = has an engine.
WaW = same base engine.
MW2 = new engine
BO = heavily modified MW2 engine.
MW3 = looks like heavily modified MW2 engine also. But may or may not be derived from the BO one. I dunno, haven't played it.
Some people are like "Same engine since cod 4" that's bs, look it up. There's no way you could miss the difference unless you aren't looking, which is fine, but then just don't claim to know anything about the subject.
My small which list for MW3:
Bring local back, BO had all local options removed, and you started at top level. Do it MW2 style please. :/
Make Spec Ops the bomb, ton of mission, they'll probably do this. Spec Ops was always the bomb, regardless of how much you complain about online vs matches, spec ops was always good fun.
Bring quick scope back, seriously it's wasn't like it was the most overpowered thing ever, it was actually pretty hard. It was just good fun in private matches and looked cool. I mean, by all means you can make it harder, but taking it all the way out with that weird mis-aim thing, not cool in my opinion.