We eat out a good deal, here are some of our favorite places in Santiago:
Kukaramacara has delicious food, and a beautiful setting at the footsteps of El Monumento. Price isn't cheap but not outrageous.
Roma is a bit before Union Medica and has amazing prices, stiff drinks, and great food.
KGB. My wife ate there and said it was delicious. I had her leftovers and agree, it was delicious. Nice portions as well.
El Turco is close to Union Medica as well, opena at 5PM and have some of the best sandwiches in the city.
Chago Burger is my favorite burger joint. On La 27 close to Leon Jiminez, close the the Lubri-Cambio. It's not an upscale crowd by any means but they have one of the best burgers I've ever had and the price is right.
SushiYa/BurgerYa is alright, nice sized portions but I think it's a bit over priced for what you get.
SuperRico close to Las Carreras and Juan Pablo Duarte is good, depends on what you order though. Prices are good but it's really hit or miss with the menu. Some items are delicious, some items are very bland.
Holy Tropical near Lovera Bar II is open 24 hours (I think) and has a nice selection of food. The prices are very affordable and I liked their food, my wife didn't like their mofongo though.
Someone mentioned PuntoDelivery, I do not recommend them.
Here's why:
They didn't bring enough change for an order we made and couldn't break the bill. We gave them the bill in full and they agreed to apply a credit to our next order (we used them frequently). The next time we ordered nobody had a record of our credit (hmm...) so we said forget it, don't send the order.
Guess what? The order shows up and they are trying to charge us for it. Great customer service and business practices...
Plus, if you call the restaurant/store directly to get your order the items are a few hundred pesos cheaper than what PuntoDelivery will charge.