Dragon Age Origins and Dragon Age Inquisition. All possible scenarios and collectables.

Kid Icarus uprising maybe. Not a super long game but the check list can be tough. After that maybe DK 64, Mass Effect 2, or maybe Skyward Sword.

No idea, but it's probably nothing significant. I have all achievements/trophies in a bunch of games, but even those tend to have some content that's not included in getting all achievements/trophies, and usually it's stuff I don't care enough about to collect. Actually come to think of it, Final Fantasy XIII might be my answer. I think getting the platinum trophy requires getting everything, and it takes a long time, so that's probably my answer. I don't know that I would do it again, but it was only my second platinum trophy, I really liked the game despite its flaws, and I guess I didn't have such a gigantic backlog back then or otherwise feel like I couldn't spend time on fairly uninteresting content in a game, so I did it back then.

If I recall correctly, at least the European version actually has fewer nodes in the Expert grid. I suspect it's the same for all versions where you have the choice.

Probably Super Mario 3D World (yes, I got all Gold flags from every character from every level)

Individually it's not much to write home about but collectively I've pretty much 100%ed every Advance Wars game and some of its contemporaries (Wargroove, Warside, etc). That type of game is my version of Sudoku, I guess.

I didn't time myself but I 100%ed Super Smash Bros. 4 and Super Smash Bros. Ultimate which may have taken a very long time, but the one I actually did time and remember was Red Dead Redemption 2 at 200 hours. Before that I remember my FFX 100% file was at 135 hours.

When I read the question for some reason the first thing that came to my mind was donkey kong 64 but I don't think it took that long to 100% it, maybe less than 100 hours. It's probably how crazy the collect-a-thon aspect is in that game that makes it stand out but it's not that different from other smaller games I have 100%'ed like a couple of Zeldas, Marios and metroids.

But yeah the biggest game I have come the closest to 100% has to be monster hunter 3 ultimate. I got almost every award in it which includes some crazy stuff like forging 10 fully upgraded weapons of each type and 5 fully upgraded armor sets. The only thing I'm missing is the gold crown award which involves hunting the biggest monsters and I'm missing like 3 but yeah it's tedious because you pretty much have to hunt the same monster again and again until it pops up because it's hard to tell if a monster is a gold crown a first glance.

Anyways I might just do it one of these days just like I plan to 100% other games like botw and totk some day. I think it's better not to focus too much on doing everything and just enjoy the game at your own pace.

The biggest would have to be Cyberpunk 2077. Including the expansion, took me over 150 hours to 100% the game. Felt nice seeing that map completely empty!

Final Fantasy XII. Well, more like 99 percent. Still have a save file where I'm working on Yiazmat.

My savefile is also midway through Yiazmat lol