Most people line these two up as competitors. They shouldn't. Epoxy is the surface you walk on and look at. Waterproofing is the bit you never see, buried below, keeping water out of the slab. Work out which problem is actually yours and the decision mostly makes itself. Plenty of UAE jobs need both anyway.
Blockwork has been the default for internal walls for a long time. Builders know it, it’s available everywhere, and it does the structural job. What it doesn’t do is go up fast or travel light. That’s the gap the lightweight panel category has been filling.
A leak almost never starts where the stain shows up. Water tracks along a joint, slips behind a coating, threads through a hairline crack, and only breaks cover on the wall or ceiling once it has nowhere left to go. By the time you spot the patch, it is usually the least of the problem.