I know it can be tough to come to a conclusion, but here’s what I got: (Note that I haven’t played Reach or ODST)
Halo CE: The Silent Cartographer
Halo 2: Metropolis
Halo 3: The Covenant/The Storm
Halo 4: The Composer
Halo 5: Blue Team/Reunion
Wow, tough choices! I think my favorite would be Halo 2: Metropolis
Mine would be Halo 2: Sacred Icon
Halo 2: Delta Halo
Call me crazy but… Cortana from Halo 3. Not because of the gameplay - hell no! But what it means: Chief keeping his promise to Cortana and fighting through hell and back.
I Personally love The Maw from Halo CE. Mostly because of the great keep escape at the end.
It’s tough to choose only one mission so I’ll list what are perhaps my favorite two missions from the core Halo campaigns. I haven’t finished the Halo 5 campaign yet…I’m trying to savor it over time while waiting for Halo 6 =P.
Halo CE: Halo/Silent Cartographer
Halo 2: Delta Halo/Regret
Halo 3: Sierra 117/The Ark
Halo 4: Reclaimer/The Composer
Halo 5: Blue team reunion ONLY BECAUSE ITS BLUE TEAM and we got to see a different side of chief that we only saw in the books. But the most badass mission IMO was Halo 2: Metropolis
Halo 3 ODST Oni Alpha Site, Halo 3 Halo (for the warthog run)
Favorite is Two Betrayals from CE, a close second is the Covenant from Halo 3.
that beach mission on CE
Sierra 117 in Halo 3.
Most of the missions that are really tough on Legendary, like Truth/Rec from CE, or Gravemind from H2 - are actually among my favorites to play on lower difficulties, cause they’re usually pretty linear and full of lots and lots of stuff to shoot, which is what I signed up for.
I genuinely like Gravemind from Halo 2 and think it is a great level. Same with Covenant from Halo 3.
My all-time favorite would definitely be Halo 3’s The Covenant. My brother and I always play this one together split-screen. It’s just an awesome mission.
Runner-up has to be Halo 5’s Genesis. The intro and Exuberant Witness were terrific.
High charity Halo2
Halo 5.
Halo 5: Blue Team/Reunion