Both locations have delicious food obviously, and the same awesome prices, but I would definitely say the drive-thru at the Thornton location makes them slower, if anything. It's easier to just get out of your car and go inside, or just drive a few more miles to the Westminster location. The people there are much friendlier to me, and my time. When you go, definitely try the new green chili. YUMMY!!!
Pros: VERY clean!, Good food for cheap, Good service