I'm from the land where In N Out is king and Shake Shacks don't exist so while I'm in DC, I sure as hell was gonna try some Shake Shack to make a comparison.
Shake Shack fries: way way better. Their crinkle cut goodness is miles ahead of the weird, cold soft powdery potato sticks that In N Out serves. You've got to get In N Out fries right when they come out, hot and fresh, otherwise they are garbage. These fries were great even after sitting about 15 minutes.
Shake Shack burger: greasy as fuck. In n Out burgers taste clean and moderately healthy. The gut bomb I just got from Shake Shack is gonna be coming out the other end with great vengeance and furious anger later on. But it does taste good. Really good. I'd maybe eat another one in another six months after my arteries recover. Both are good burgers but I'd give the edge to In N Out for having a cleaner flavor and never feeling like a lead ball in my stomach.
The other thing that makes Shake Shack great: you can get booze there. After getting nailed in the femur by a small child with an umbrella at the portrait gallery, I think I deserved my favorite nerve-relaxing agent. I hate children. I love wine. They have decent wine, by the way.
Also they have wifi. I don't know if In N Out does because I always do the drive thru.
I might get, and regret, a chocolate concrete too. Regret because dairy doesn't always get along with my bowels. But I wanna try one. Because yolo.
Now let's have a lively debate about whether In N Out or Shake Shack is best!
ETA: Write-ins welcome! Five Guys....and whatever else!