Answer
$HClO$ is a stronger acid.
Work Step by Step
The difference here is the central atom: $Br$ and $Cl$.
To determine which oxyacid is more acidic, we will have to identify which central atom is more electronegative.
$Cl$ is more electronegative (They are on the same column, and $Cl$ is closer to the top.)
Therefore: $HClO$ is stronger.
