dory most often is imported vietnamese basa rubbish

barramundi cannot overcooked, else taste very rough, dory over cook no difference

Not every batter is the same. Besides fish species, batter is important to a good quality fish and chips.

How chips is cooked contribute to the overall experience also.

Arthur's at Shangri-la serve a jolly good fish and chips.
Pangasius aka Basa/dory belongs to the same catfish family as Patin, may be affordable but is not inferior. In blind rest, few if any could tell the difference between patin and dory fish fillet.

Small size e.g 500g barramundi aka siakap or seabass may be affordable but big size e.g >5kg is a lot more expensive. Few places in kl use big size barramundi for fish and chips.