Makes me wonder if MCC sold better than Halo 4.
There's no way. Halo 4 supposedly sold over nine million copies, while Microsoft hadn't even shipped ten million Xbox One units to retailers as of last November. Assuming those all sold through, and we count 1.2 million holiday unit sales that were reported, and we tack on an incredibly optimistic eight hundred thousand units for this month, that's a grand total of twelve million copies sold.
That would mean 75% of Xbox One owners would have had to have purchased Master Chief Collection just to tie Halo 4's sales. Even without all the negative controversy, there's absolutely no way a title would reach that much of an install base.
Halo 2 my opinion had the most auto-aim and sticky-aim of any Halo...and I agree, the shooting wasn't difficult at all, but it did make for a great competitive pvp game.
It definitely did have the most autoaim. However, it also had the tightest controller response for aiming and player movment. No other game in the series has the same sense of responsiveness, immediacy, and connection in its aiming and movement that Halo 2 did. Those things were a big part of why I loved that game: it just "felt" right. Like you said, PVP was still good (CQC is without a doubt the best in the series) despite the overzealous autoaim.
Halo 3 I might've liked a lot more if it weren't for the projectile BR and the aim acceleration and movement being so awful. As one of my friends describes Halo 3's movement, it's like "ice skating."
I will say that Halo 5 seemed like a major step in the right direction in that regard. Movement is still off in that base speed is low, sprint is, well, sprint, and clamber makes my soul hurt. But responsiveness seems pretty good and consistent. Unscoped aiming feels really good as well (though I might suggest upping autoaim a tiny bit to speed up gameplay), but the actual scoped weapons, especially the DMR and sniper, felt really weird when scoped.