Hi Kushal: How do you decide which brand of clothes do you wear? Can you comprehensively gauge the quality of the shirt/trouser just by looking and touching it?
In case of ply selection, I would suggest to first of all look for the ISI mark and number, check that the ply is water resistant 'BWR grade'/Marine Ply or ordinary "MR grade" as per its application, finally take a decision based on your budget.