You know, I do enjoy Reach despite its many flaws, and I have defended it in the past.. That said, I recently picked up Halo 3 and man did it click.. while the game is perfect, it is very refreshing to play compared to Reach, and I really hope Halo 4 can capture best of the Halo 2/3 gameplay.
On the subject of remakes, while tough here is my list of wants:
Lockout
The Pit
Guardian
Valhalla
Terminal
Midship
(And almost every other map from Halo 2. My god where they good.)
While Day 1 DLC is a sour spot for most, and for good reason, I think Gears 2 handled it well with the 'flashback mappack'. I would love for 343 to get something out like that which comes free with every new copy of the game, maybe they could work with Certain Affinity again to get some remakes out there while 343 ships the game with new maps.