If you've lived in Denver for any amount of time, you already know Santiago's. It's one of those places that just does everything right without trying too hard. The green chile tastes like it's been made the same way for 40 years, and honestly it probably has. Fresh tortilla, fluffy eggs, and that green chile has this deep, slow-cooked flavor that you can't fake.
I always go through the drive-through on Saturday mornings. Get it smothered. You're going to spend like eight bucks and leave completely full. The tortilla somehow holds up even when it's drowning in chile, which is more than I can say for most places. If someone's visiting Denver and asks me where to go first, this is it every time.