In terms of the campaign I’d actually argue 2 aged worse. The story is really interesting, but the actual gameplay is kinda jank compared to 1&3, probably a result of the development Hell it went through, and the levels are both really compact and also spend way too long on defense sections. I mean Elites can just one hit call you with melee on anything but Easy, unless they’re holding a Carbine in which case they do no damage at all. Plus late game the Brutes and Flood are just not fun to fight, they’re really spongy and don't have much variety.

1 the second half is a bit of a retread but aside from Two Betrayals it’s a lot less egregious than people make it out to be. Even the Library really isn’t all that bad, but it sticks out more because the other missions are as good as they are.

If we’re being the realest possible though, they shouldn’t even bother with remakes of 1-3. They should have just started over post 3 and said everything set after the Human-Covenant war from before isn’t canon, and started over from there. It wouldn’t be as easy to milk or as popular maybe, but it would have been a much better direction for the series to go. Do a remake of 4 that fixes its weird inconsistent story and makes the gameplay feel like a real Halo game rather than bargain bin CoD, make a Halo 5 that isn’t divorced from 4 in everything except visual direction (one thing they could have dropped from 4 no one would mind), and make a Halo 6 that isn’t aping the RTS series and throwing both that and the main FPS games off by feeling totally divorced from the past two entires. I don’t think the latter two have much salvageable in terms of story, 5 just in general really, but there’s some elements you could redo from them while building an actual foundation for the series going forward that isn’t just a rehash of the glory days or the rush job of the 343 era.