I'm with shmem, in that $op_map{$op_choice}->(@args); is the form that feels the most natural.  Such a technique is commonly called a "dispatch table".

But it's worth noting that a good to habit to get into is to put a comma at the end of each line, including the last.  So you're safer if you put a comma after \&op2, as in:

my %op_map=(    'OP1' => \&op1,
                'OP2' => \&op2,
);
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That's because later, when you add a function or functions at the end, you won't get an error due to a missing comma.