Top Spot is the top spot in Kuching!
Went there multiple times it was so good!
Do not just sit down anywhere, where you sit determines who will serve you. People will ask you to sit at their table so that they can serve you. So ignore their offers, pick the stall that you want to eat from first (peruse what is available), and then sit at their table. Once they have acknowledged that you are sitting there (many of the tables are reserved), you go up to the stall itself and pick what you want to eat and how you want it prepared. It's very busy, so go early, late, or make a reservation in advance.
For seafood, I recommend stall #25 Bukit Mata. They have a wide selection and many live seafood items in tanks. They do not serve food out of season, so they might not have all the items others are selling, but you will be getting fresh food. The daughter, Lynn is very knowledgeable and helpful. You won't have many opportunities like this, so splurge! Go for delicacies, exotic items, and preparations you would have a harder time finding elsewhere. The area is known for fern vegetables, for example. You can ask them to weigh the food for you before making it so you know exactly how much you will pay.
I also recommend the sugar cane juice, which is at a stall in the plaza away from the seafood. the juices they serve at the main tables is pretty lame. There is also another stall in the plaza area that makes traditional bamboo chicken and a fabulous uncooked jellyfish chili-lime salad.
Hint: there is a lift from the bottom of the car park on the opposite side of the visible winding staircase. Take it to floor 6 and you will be placed near the thick of things.