Random array

array_rand

$ads = array('<a href="#">Sponsored link 1</a>', '<a href="#">Sponsored link 2</a>', '<a href="#">Sponsored link 3</a>');
echo $ads[array_rand($ads, 1)];


OR

$numb  = rand( 1, 3 );
if ( $numb == 1 )
echo '<a href="#">Sponsored link 1</a>';

why not this?

<?php
$numb  = rand( 1, 3 );
echo "<a href="#">Sponsored link $numb</a>";

Because each array is a different message..

Ah, your initial example showed them as the same except for the number, in that case scenario 1 is probably my preferred approach, but I'd list each element in the array on each line since they're long strings, it's easier to read/modify later

The first method will probably look cleaner than the other depending on how many different links you end up with.