It depends on what happens to the product after it arrives, and the honest answer is
that neither is better in the abstract.
IQF means each piece is frozen individually and stays free-flowing. You can pour it,
weigh a partial quantity, and return the rest to the freezer without the pack becoming
a solid mass. That suits retail packs, food service portioning and any industrial
process that meters the frozen product rather than thawing the whole unit.
Block frozen means the product is frozen as a mass in a carton or a tray. It is cheaper
per tonne, because the process is simpler and the throughput higher. It is entirely
suitable for a plant that will thaw the whole block anyway – purees, soups, sauces,
ready meals produced in batch.
The trap is partial use. A block that is opened, part used and refrozen has been
thawed at the surface and refrozen, which costs quality and creates a documentation
problem. If your process cannot consume a whole unit, IQF is not a premium, it is a
requirement.
Two practical points. IQF free-flow is a property that degrades: a product that has
been temperature-abused in transit arrives clumped even though it left the plant
free-flowing, so clumping at intake is a cold chain finding, not necessarily a
production fault. And the two formats have genuinely different prices, so specify
which one you are buying rather than assuming from the supplier’s website.