I don't want to add to the flames, but it's a clear and present fact that in any direct combat scenario, Halo requires both weapon choice, maneuverability, and [as of Reach] utilization of armor ability, as opposed to Call of Duty's aim and shoot-- anything else is just having the drop on somebody.
Shield's just add another layer to the combat strategy because depending on the range and fighting space, some weapons will be better than others, and sometimes having tools like the Plasma Pistol can change an experience completely and catch the opponent off guard; this can last a surprisingly long time per encounter whereas the average CoD encounter is 3 seconds as per kill cam.
This isn't me talking shit about Call of Duty-- hell, I played Black Ops 2 at a friend's place this weekend and I think it's the best one since MW2; I bought it last Wednesday, and I'm about to start it for myself tonight for the first time. It's a spectacular game, but comparing it to Halo in terms of gameplay assessment (or anything else for that matter) is and always has been ridiculous.
~Est. 2007~