hmmm... manguito is popular but personally i never liked it. the food is just so so and service slow. then there is dominican food eaten by dominicans and dominican food eaten by gringos

there are plenty of "plato del dia" type of places serving fast dominican lunch of rice, beans and meat.
armando's has toned down and has a dominican buffet now. located just next to casa nelson, on the corner.
supermerkado tropical has own cafe and the food is good and cheap.
kilometro zero on luis ginebra has variety of foods, some dominican stuff included like mondodgo and excellent chuletas.
there is a lady selling empanadas, two corners away from la sirena, from the balcony of her house. nice stuff.
just off luis ginebra, close to the police there is a sandwich place, open in the evening and their food is good. prices are quite high but their 200 pesos supreme sandwich can feed two.
next door to our pharmacy there is a dude selling fried chicken. night only which is a bliss as you cannot see how black is the oil he uses

but damn, pollo is fantastic! just the smell will make your mouth water.
and of course there is maimon and the fish. excellent food and low price. i like the place that is almost last on the feft (coming from POP towards santiago), just opposite from large plaza style bar. heck, most of those places are great, i guess.