Nodes prefer the first heard among those with otherwise equal work.
How often does it happen that two miners simultaneously find a block with exactly equal work values?
The issue here is the definition of work. Work is based on the
target, and not based on the block hash itself. It is a statistical fallacy to claim that a block with a lower hash required more
work than another block mined with the same target.
When two blocks have the same
target, the earliest-received is preferred.