My title of choice would probably be Daggerfall because it’s just so ambitious and truly offers an experience none of the other elder scrolls games offer. That being said it is kinda an example of a sequel eclipsing it’s predecessors as well given it is more or less a straight improvement over Arena in every way.
Likely controversially, I’d say Portal.
Yes - the sense of exploration and discovery in Portal 2 is a good thing, but the puzzles, which are necessarily a central part of the game, are IMO much less engaging than the ones in the original.
The thing to me is that the Portal 2 puzzles are more complex and involve more tools, which actually makes them much less of a challenge and thus more of just a pointless chore.
In the first one, I had to think creatively. I just had a room and a small set of tools and had to figure things out. There were some hints - ledges to jump off of and such - but the solutions were still complex, and complex through the creative combination of a handful of simple elements, which is exactly what makes a good puzzle
In the second one though, there were many more and more specialized elements to the puzzles, and that meant that most of the time I could do it without even having to think much. I’d just go into a room, take this new item that’s obviously meant to be used in some particular way and use it in the spot that was obviously set aside for it’s use, then take the next item that can only be used in one particular way and use it in the place obviously set aside for it’s use, and keep moving around the room that way until it was all assembled, then just trigger it and be done with it and go on to the next one. And that was disappointing.
Portal 2 is a good game. I just think that, all in all, the first one was better.