Halo 4 was a great game in it’s own right. But Reach was, and still is, my favorite Halo game ever.
I got my CQB helmet back. The Jetpack in this game is actually useful. Vehicles actually stand a chance without everyone running around with Plasma Pistols and Plasma Grenades.
Oh… and Firefight. Spartan Ops was kinda fun, but I definitely prefer Firefight with all the customization options, the freedom to tweak the game to my hearts content.
Only thing Firefight is missing are heavy vehicles and aircraft; I’d love to have a large Firefight map with Scorpions, Gauss 'Hogs, drivable Banshees, and lots of enemy vehicles to blow up (+ friendly AI, just like on Installation 04); and a Firefight Heavies gametype to go with it. But I suppose it’s too late for more Firefight DLC…
There’s also the little differences; I really hate the brand-new sound effects they used for all the weapons and vehicles in Halo 4. I prefer the SFX for Halo:Reach, seeing as the Halo 4 Warthog sounds like an RC car and the much-desired Battle Rifle sounds like a cheap airsoft gun… but really, there are few weapons and no vehicles in that game that don’t sound like crap.
I really wish 343i would renew support for Halo:Reach. A few playlist updates, maybe… like a DLC playlist with all the Noble, Defiant, and Anniversary maps. I’d like to play the maps I bought, and there’s still 3 achievements for the Defiant maps I haven’t gotten. Reach still has a pretty good population (better than Halo 4, in fact) so that’s not an unreasonable request.