I keep on coming back to the following restaurants/stalls for the food, ambience and people. In no particular order:
Thaba's - fantastic North Indian food. Fish masala is great as is the eggplant dish.
La Risata - good Italian at a reasonable price
Pizzeria Uno - fantastic pizzas. home delivery available, only if they're in the mood
Burger stall right across Hawaii barber in Ampang Jaya - extra mayo, extra coleslaw
Restoran Murni next to 7-Eleven (Roti Boom area) - nasi lemak and roti canai in the mornings
Nali's Corner - try the rendang sandwiches
I promise to update this list.