I don't really have one favorite game, so I'll mention the worst ones I have found.
-Farron Keep in Dark Souls 3. I hate swamp zones and the first time through it's an incredibly dull drag.
-The search for Dandelion in The Witcher 3. Seriously screw that quest line. Just an enormous amount of unenjoyable tasks. Luckily the rest of the game is amazing.
-Perfect relic in Bears Repeating, Crash 4. If you have played it, you know why. Building Bridges as well for the same reason.
-The stupid timed marauder event in Doom Eternal. Didn't help that I was out of extra lives and with basically no ammo. I restarted 10 times and I was afraid for the rest of the level, thinking that was going to be standard difficulty.
-Arkham Knight's Riddler puzzles. Over 200 annoying riddles/collectibles. I didn't even try, I just followed a guide step by step. Unfortunately needed for the true ending.
-Shadow of War endgame. Admittedly I liked the game a lot, but only before I realized it's just a copy of the first with bigger scale, worse plot, and absurd restrictions. Maybe it's fixed now, but the endgame back then was basically winning 20 sieges. Sieges are 30-60 minutes slogs full of painfully unskippable cutscenes (one for each enemy captain). If you die ONCE, the siege is failed, and you must restart it from the attacker side, since you lost the fort. Took out any fun I had with the game.