a <div> is a logical division in your content, semantically this would be my first choice if I wanted to group the heading with the list:
<div class="mydiv">
<h3>The heading</h3>
<ul>
<li>item</li>
<li>item</li>
<li>item</li>
</ul>
</div>
then you can use the following css to style everything together as one unit
.mydiv{}
.mydiv h3{}
.mydiv ul{}
.mydiv ul li{}
etc...