If I had to guess, Metal Gear Solid 2, but hard to tell. Ten-ish would be a decent guess, but could be more, could be less. If it's not that, then it's probably Metal Gear Solid 4, with probably nine playthoughs. I think I played it seven times when it came out, then once more soon after it got trophies, and then once more later.

Great analogy. Some of the best quests are in the DLC's indeed but I do Love Skellige, the quest with the baby and the fire, the poor cursed werewolf who's food turn to Ash in his mouth and even the little stuff like the monks vow of silence. God that game is absolutely superb it still amazes me and it'll be ten years old in May. 😟 

Top 3 would probably be:

RE4 x10
Uncharted 2 x7
Metal Gear Solid: Twin Snakes x3 or 4

Tbf you’ll probably find a lot of people are very much the same as you re: the last part. Without the DLCs, I’m not sure TW3 would be my favourite game ever. The base game is incredible, and I love it, but the two DLCs combined push it into almost unsurpassable territory. From the moment I played, they have both stuck with me. Gaunter O’Dimm is one of the greatest characters ever created (and Dead Man’s Party is one of my favourite quests in anything, ever) and Toussaint as a region, well… I actually have some kind of messed up heartbreak that I can’t live there. Yep, I mourn for a fictional place. The soundtracks to both are also phenomenal, and I listen to them regularly, Blood and Wine particularly getting to me and still bringing intense emotions to the fore. I could go on and on but you may get my point by now.

The only reason I’ve only completed the whole game twice is because I hold it so sacred and so profound is the impact it has on me, that I feel it would dishonour it somehow to overplay it. It also feels like such a complete game to me that after the ending of Blood and Wine (THAT ending at Corvo Bianco) that I always end it there. It wouldn’t feel right for me to continue to play. Man, I really don’t think any game will ever top this experience for me. It truly is something beyond special. And I’m stopping now as I’m feeling emotional.

You've convinced me to do another playthrough, I was gonna wait till I grab a PS5 for the next gen patch but man, well said.

God knows how many times I have seen the credits of Star Fox 64. It’s definitely the winner by far, should be dozens of times. But that’s a short arcade style game. For the rest I beat several of the big main Zelda games around 5 or 6 times over the past decades. I think I beat OoT the most, I think six times, including the Gamecube Master Quest and OoT3D, but not always 100%. Besides that I think I beat Knights of the Old Republic 4 times; light and dark on male and female. But now that I think of it, I might’ve beaten KotOR2 more because of the restoration mod.

Most of the time in my life I’ve been playing endless games though, like city builders. I played Anno 1602 or Rollercoaster Tycoon 2 thousands of hours probably. Can I just divide that by 40-ish and say I beat those 100 times?

Lol, no. But there are end points of those types of games, no? I've never actually seen it through but doesn't City Skylines have objectives you follow or is that just a guide? Not sure about roller coaster Tycoon but Theme Hospital and Two Point, my go to's can be beaten, it's very difficult to do but it can be done.

Maybe FFX, 6 times?

Hard to quantify other games, especially as a PC gamer, for example

Dynasty Warriors 3

I beat every character at least 5 times. That's 32 characters x 5 = 160 playthroughs.

World of Warcraft

I got multiple max level characters and cleared the highest available content at the time.

Hearts of Iron 4

I have completed my goals with certain countries multiple times.

Civilization 3

Similar things to HOI4, and scenario completions.

Probably Super Mario World (at least 20 times) or Pokemon Blue (900+ hours across 15+ playthroughs)

I forgot action RPGs altogether, so add Titan Quest and Grim Dawn to the mix. I don't even want to guess how many times I've completed them, but you can possibly count the times in dozens...