My gaming career began at a young age, 12 years old with Ever Quest - before I sold my account for $600, I had over 18 months of /played time.
Then World of Warcraft - I played for years, clocking in over 24 months of /played time - which I tried to sell, but the leveling/market was so flooded with chinese gold farmers by that time it just wasn't worth it.
Other contenders, Civilization, Counter-Strike, Tribes - probably clocking in at least a few months each.
And 1 more that I didn't list because it's not a popular game - Dransik - a very primitive MMORPG, and actually my first. I started playing it when I was about 9 years old, which is how I actually learned how to type. I played it religiously for 3 years, during which I made over $1000 selling various gear/equipment. It also did not have a /played function, but I guarantee it was at least a year's time spent there, minimum.
The literal years I spent playing these games were fun while I was playing them, and at the time it seemed like time well spent - but the truth of the matter is... it wasn't. Especially the WoW experience after I had already turned 18 and was out of school.
My vast amount of experience playing these games taught me one thing - that all these games are the same.
They're designed to make it feel like you're accomplishing something, when really you're not accomplishing anything other than wasting your time - which they want you to do because you pay for a monthly subscription.
World of Warcraft was the worst at this, by far. They add "expansions", "new content", that is the same thing just redesigned to look slightly different.
Ever Quest was the coolest, it at least was designed around community. Unlike all the other MMORPG's, Ever Quest required you to "party" with other people to level, and even more people to get the best gear by "raiding" with 60+ people. And if you were incompetent/unreliable, people would remember you and bar you from their parties and raids. All the other games, you could reach maximum level/gear playing solo, which they did to market to everyone so they could get more subscribers.