Good luck man. Forgot about the beta armor. Guess I'm gonna have to marathon it.
The only memorable moments of the game for me (that weren't cutscenes) would be on Requiem when you leave the crash site and the music just perfectly ascends to show off this majestic view. Really disappointed that the game wasn't more open. The other moment would have to be the Star Wars level where you fly a space fighter through a trench. That was actually pretty cool.
Composer deserves to be counted as one of the great Halo levels across all the games, IMO. Got a nice mix of all types of combat. It's a shame that Midnight fizzles after the really fun space section.
I think how you rank the games also depends on what elements of the game you react most to--I find Reach far more tedious in places because while the level design is pretty great for large stretches, the sandbox just makes encounters less fun. Bullet-spongy enemies or not, I feel like I have far more options for engagement in Halo 4.