#!perl -w
use strict;

while( <DATA> ) {
    chomp;
    my ( $data ) = m/TAG:\"([^\"]+)\"/ ? $1 : m/TAG:([^\"\s]+)/ ? $1 : 'not_def';
    print "$_ => $data\n";
}

__DATA__
TAG:"test of data"
TAG:test_of_data
TAG:test of data
TAG: test
TAG:test of data"
TAG:"test of data
TAG:test-2_3.we