$arr = array('blue', 'blue', 'green', 'yellow', 'red', 'red', 'red', 'orange', 'orange', 'orange');
$counted_arr = array_count_values($arr);
$max_repeats_count = max($counted_arr);
foreach($counted_arr as $key => $value)
{
if($value === $max_repeats_count) echo $key, '<br>';
}