SoM is relatively short and easy to just blast through. It's nothing special, but fun enough for the amount of content it has.
Everything I saw of SoW suggests that it was far more bloated and required more grinding (though they may have changed things when they got rid of the micro-transactions).
Steam says I played Mordor for 59 hours.
I played War for 121 hours.
Mind, I DO play very slow, get side-tracked, and played both to 100% completion (base games, not DLC). Like, I spent 15 hours in the first map of Shadow of War before I could even use the Nemesis system, because I had so much fun thinning out the orcs' ranks--until the game spawned 2 Trackers that were like 10 levels above me, and then I had to run away and move the story along.
I was very impressed with everything in Shadow of Wart (except the story; it was passable), and despite the abundance of loot, the game didn't feel bloated. There's a bunch of collectibles, but they're all relatively close to key locations (outposts), so they're easy to grab, and collecting a full set per area grants you an extra skill point, which are super-useful, especially early on.
The balance between main + side stuff in Shadow of War is not quite as good as Arkham City (which is my gold standard), but it's pretty close; and the Nemesis system turns the gameplay into a mix of Batman Arkham and Pokemon.
Mordor is just.... lacking. The game's core premise takes 80% of the game to take off, and the icon-hunting felt a lot more repetitive and more of a chore.
