Hoo boy. I don't think I fit into any of these, but I sorta also fit into all.
Gamism got me into DF. 40d was the first version I played. I was looking for roguelikes, and saw DF mentioned a bunch. The description of it as a complex RTS got me interested. That was years ago. I think it was the simulationism that got me hooked. I remember when I was younger how I would rage at Age of Empires 3 because "WHY ON EARTH are they HITTING THE TREE WITH AN AXE, it has ZERO HP, but it's STILL STANDING and I'M GAINING WOOD!". The lack of realism killed it for me. Suddenly, Dwarf Fortress came along and it was glorious.
Now, I almost roleplay DF. I do what's logical. I guess that would be simulationist? Maybe? I dig in and plot out a massive Great Hall that I'm working on by the first summer. Because it makes sense for my dwarves to do. The fact that it's 5 Z-levels high has no bearing on the outcome, save that it takes more time, but it feels right. It's not constructionism, because I have no desire to use all my gold to cover the floors in the hall... I do that for the nobility's chambers. Because it makes sense.
But then, there's the challenge of it all. The management. I love the fact that all the resources are actual game items, not just numbers, that if I want to stockpile all my wood here, I need more space. And then the sheer "awesome" factor that makes me build a bridge across a massive artificial chasm and put a ballista battery on the side. Useful? Nah. But awesome to knock invaders off and watch them tumble 50 z-levels. Or collapse it under them, Khazad-Dum style. I'd have to say that the awesomeist (new category!) are what keep me coming back, if it's because I can have beehives now, or because that goblin is dragging his guts around, or because WAIT WHAT IS THAT A HOLLOW SKIN AND IT'S WALKING OH ARMOK NO! Toady has done magnificently delivering the awesomeist features, and his creativity is unparalleled. As long as that stands, I'll be here.