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.







