I do recall KI's body being a lowpoint, but I recall the dragon race being a further drag.

The dragon race doesn't bother me as much as Ki's Body.
* It's a lot shorter, and it's linear so you don't need to keep track of where you've been and where you haven't. That's not the case in Ki's Body. (Also, it's not a roadblock the way the Venus fight tends to be.)
* In a non-glitch playthrough, by this point in the game my party is already fairly well established; in particular, human mages (one of my favorite builds in this game, even though they're more late bloomers) are already effective, and a robot can use a bazooka if needed (or that one weapon in the DS remake that is slightly stronger, can stun and lower agility, and can be found in a trapped chest in the sewer; or I could just get a Venus fan (AGI-based damage to an entire group)).
* In a glitch playthrough (not possible in the remake), I have the Pegasus MAGI at this point (trashcan bug in Apollo's world allows me to skip ahead and get this), so I can just warp out of the dungeon, taking my dragon with me. (The dragon can fly over any terrain, can come with you into towns and dungeons, and lets you go through walls in them.) On the other hand, Ki's Body comes before I can use the trashcan bug to start glitching.

ah , yeah that was harder than expected , and they still put escort missions into games , who likes those...

The sewer level in Duke Nukem is one of the best maps in the game though.

I certainly don't like escort missions, no matter the game. I liked the setting in BioShock and a few other things, but I do not have fond memories of Proving Grounds.

The darn mini-helicopter mission in GTA:VC. Most horrible controls ever...

The construction site in Max Payne 2, that shit just goes on forever killing the same cleaner dudes in the same environments over and over. A massive blot on an otherwise enjoyable game.

The final mission in Mafia Definitive Edition. The aiming was so rubbish I cursed the game, despite enjoying overall experience.

Almost every single level in Unreal 2.

The starting temple in Fallout 2 potentially. But thankfully it ends up only being a tiny part of the game, and you 'cheese' your way through it if you know how.

The damned catacombs in the first Thief, or worse, Thief's sewer gangs level. It was bad enough for me that I'm not even half considering playing the game again. I'd much rather jump straight to Thief 2, with its more 'thievy' levels.

4/5 of all classic RTS levels with no base-building.

Ultima 1 has spaces battles? I only played Ultima 1 for like ten minutes before giving up. Its controls were a bit "too old game" for my lazy self now.
Nothing like pixel-perfect stealth required to avoid the tank from being alerted to your commando and racing to squash it. Argh!

I found that most/all such levels where you actually have a commando type character, are actually great. e.g: Tanya in Red Alert, Raynor in SC, the mutant with the raygun in Tiberian Sun, or the original commando from the first CnC.

Instead it's usually those levels where you only have normal troops at your disposal that I find so frustrating.