Played every single one and those two are my favourite Halo games.
Reach is a perfect standalone Halo game, and i loved the experimental design of ODST's campaign. If you're into Destiny, ODST is almost like Bungie's attempt to demo an open world that encourages exploration.
How does it encourage exploration? The only thing to do in the environment aside from shoot things is find the audio logs. The environment might have been large and interconnected but it was devoid of activity.
I also preferred ODST and Reach's story modes to any of Master Chief's games.
ODST is an odd one, because it's intentionally designed like a noir story. Your character is just trying to piece together what happened to the rest of his team over the previous several hours, it's full of jazz music to evoke that detective story feeling, and there's a lot more quiet moments than other Halo games. Very different style of game, but that's why I liked it. Also, the cast of Firefly basically does all the voicework, so if you liked that show it was kinda fun to see them together again.
Reach is just a really well done campaign. The levels are all unique and varied, the characters are better developed than anyone in the MC games pre-H4, you get your own custom character to play as, and the story is appropriately bleak and painful. It was a fantastic game, the height of Bungee's work on the series. Most of the hate I see for it is because of the changes to multiplayer, which have nothing to do with the quality of the campaign itself. --- The big brain am winning again! I am the greetest! Now I am leaving Earth for no raisin!
As far as campaigns, I enjoyed them both quite a bit. ODST had a very good campaign IMO. I loved the dark atmosphere and the soundtrack was excellent. Reach had my favorite overall campaign. --- GT:Triple S 06 Steam ID:triples22
Both of them are good. I like Reach more than ODST but don't buy Reach, it's free the latter half of this month on 360. --- GT: CynicalRaptor26//PSN: DuodecimKnight//Steam: Soontowait FC: 2981-6641-9175//NNID: RaptorCats//Origin: SecondcityTakk
ODST is awesome, people just didn't like that it used halo 3's mutiplayer, but its one of the better campaigns they've done. Reach is good but nothing special, i'm sure its dirt cheap though. --- Humanity as a whole gets dumber every time you write sonypony nintendrone or xbot...and weeaboo...I mean, honestly people.