People hated Judgment because of multiplayer, not because of campaign.
And for a Gears of War game it was indeed a horrible piece of shit. Blindfire reticle, no DBNO, no perfect active reload damage, no stopping power for guns, KotH mode changed to a 3-hill Domination bullshit, asymmetrical maps and only 4 of them and so on. Even things like vertical movement felt out of place in a game like Gears of War and made the game look like a bad joke. It was like any other fast paced 1st person shooter. They even killed gnasher duels with that overpowered melee. No need to master the hipfire, just hit B to stun enemy and deal massive damage, then shoot with a blindfire reticule WHAT THE FUCK IS THIS SHIT?! Then they took back centre-screen aiming too instead bullets coming from the tip of your gun like it was in Gears 2-3.
But I thought campaign had a good gameplay. Iirc most of the gameplay changes were only for multiplayer and stuff like DBNO were still in the campaign. It was just that the story was non-existent and Baird just wasn't good enough for a main character. I remember it being fun to play though.
Then there was Overrun, a masterpiece of a multiplayer mode. It only had 4 maps but I'd say Overrun alone was worth the 60€ I paid for Judgment. Played the shit out of this mode and I so much hope they'll bring it back for Gears 5. It would bring in more casual players too.
I've been playing alot of Gears of War 4 multiplayer lately, mostly my favorite mode King of the Hill. I'd say it's overall the best Gears of War game by a big margin, actually. You might want to check out the campaign. It has that dark and gritty feel of original Gears but with with more exciting and better pacing of action.
Im no judge of MP, never got that into it. Gears 3 is the 360 game most people still play online so I will take your word for it. The Overrun mode is actually pretty fun, I llayed a lot of that as well.
I like Barid and the story was okay as a side thing. The only weak link in the characters was the girl, I cant even recall her name. Anywho, I dont think the story was bad per se, its how it was told thatvwas underwhelming and the game feels on lower budget side with especially in cutscenes.
I just realized Gears has never had a large scale MP mode. Curious to see if they try new modes in Gears 5.
I got a X1X recently so Im going to replay Gears 4 again but in 60 fps this time. In my memory is wasnt great at pacing but I tend to appreciate these games more after a replay. I primarily played the co-op modes in MP and its great, more of the same just refined.