Alright. Allow me to give my thoughts:
Now assuming the game flowed like:
(Halo CE = Halo 5) → (Halo 2 = Halo 4) → (Halo 3 = Halo: Reach) → (Halo: Reach = Halo 3) → [343 take over] → ( Halo 4 = Halo 2) → [MCC, including 5, 4, Reach and 2, with remastered Halo 4 that no one would want, apparently] → (Halo 5 = Halo CE)
Halo CE/5 – Favorable reviews. Generally considered by Halo fans to be one of the best. Seen as a little weird by the rest of the gaming community.
Halo 2/4 – Adequate reviews. Given props for first game with online multiplayer. Generally considered pretty crap by the community as gameplay is so different from CE. Spawns some players that will like it out of nostalgia, though.
Halo 3/Reach – Good reviews. Given props for not being as sucky as 2. Players who liked 2 may dislike 3 out of nostalgia. Others may see it as a step in the right direction.
Halo Reach/3 – Good reviews. Given props for extremely balanced gameplay, better than Reach or 4. Disliked for the lack of AAs. Liked for the tight gameplay and reliance on strafing and map control, a la CE. Disliked by the 2 crowd, has 3 crowd split. Tolerated by the Halo CE crowd. Brings many new players in because of its uniqueness compared to other games in 2010. These players are mostly seen as noobs, but some are veterans of other games drawn to Halo’s weirdness.
343 TAKES OVER
Halo 4/2 – Very few bugbears can be directly contributed to 343 at this phase, simply because actual Halo 2 and actual Halo 3 are more similar than actual Reach and actual 4. It might get called out for not changing enough, or throw the 2 crowd into a fit of rage because it’s the perpetuation of everything they dislike, despite being at odds with both the CE and 3 crowds. CE crowd tolerates it. 3 crowd likes it. Reach crowd loves it. Good reviews. 343 generally in good standing with the community, scept’ the Halo 2 players. But few actually liked Halo 2. Biggest complaint: Basically Reach.
MCC debacle – Makes the 2 crowd even angrier because it’s the anniversary of their game. Annoys the rest of the games’ fanbases, not only because the game is broken, but because few of them actually liked Halo 2. However, because a portion of Reach’s sizable fanbase enjoyed Halo 4, 343’s mess ups are somewhat exaggerated by the Halo 2 crowd and the Halo 2 crowd only.
Halo 5/CE – Favorable reviews. CE fans enjoy the faster pace and low kill times and Reach and 4 fans love the tight gameplay and fun arena slaying, though the low kill times do put them off a bit. However, Reach and 4 are seen as a build-up to 5, rather than as 5 redeeming a studio. Old players are still a little miffed by the lack of movement options, though.
I honestly think the mechanics speak for themselves. I know people are probably going to disagree, and I have to say, this isn’t really subjective. But we’re talking about hypothetical situations in pretty specific scenario. It’s really -Yoinking- hard for me to be subjective.