It's hard to say. The 1,000 hour ~ 2,499 hour range is what I chose, as I know for a fact I have over 1,000 on hours on several games. Steam indicates that I have somewhere around 1,100 hours on Path of Exile, if I recall correctly.
Just checked, and Path of Exile is at 1,157 hours.
1. Path of Exile: 1,157 hours
2. Torchlight 2: 464 hours
3. Dragon Saga: 281 hours. Formerly Dragonica, a grindy, Korean, F2P MMORPG which I had originally played many years ago with my wife back in the days when MMOs were a dime a dozen. I found it on Steam a couple years back and started playing for old-times sake. The game is practically dead now, and it is constantly having server problems. It was down for several days in a row I can recall.
4. Skyrim SE: 195 hours. I also have 121 hours on the original Skyrim release, so if I bundle them together that would put Skyrim at 316 hours.
5. Fallout 4: 160 hours
Of course, this is only Steam, which is a fraction of my gaming. I play WoW usually for two months at a time every couple of years, and I would estimate that I have close to 100 days of playtime, which is the threshold for the next tier in the poll but I am unsure, and my best guess would be something around 90 ~ 95 days played. I have no idea how many days of playtime I have on FFXIV. If my sub was active I could check, but my best guess is 35 days.
Smash Bros. Melee is also a very top contender. I felt like I played it everyday for years during my childhood, but more accurately it's probably been around 500 ~ 700 hours.