I dont think it really matters. although this shortcut might save you some time:
PHP Code:
<tr>
<td><?=$data['key1']?></td>
<td><?=$data['key2']?></td>
<td><?=$data['key3']=?></td>
</tr>
<tr>
<td><?=$data['key4']?></td>
<td><?=$data['key5']?></td>
<td><?=$data['key6']?></td>
</tr>
also, if you are using echo(), you really don't need the parenthesis if you don't want.
and, if you are only echoing a variable, then you don't need the quotes.
PHP Code:
<?
echo $data['key1'];
?>
but then it's all up to you and how you prefer.