The angular guidance says that you should use the “element” restriction whenever the directive has full control over it’s template meaning it has a template that it is rendering out, etc.
For attributes, they suggest to use these only when you are adding “behavior” to an existing element or decorating an existing element.
For example, think of the ng-click directive, this is used a attribute not as a element because the click directive is just adding the click behavior to some element.
Another example would be the ng-repeat directive, it is also used as an attribute not as a element because it is going to repeat the element in which it is being used in.
Now, this guidance is from the angular documentation; however, I don’t know necessarily that element vs. attribute is going to give you a “better” approach it’s more of a convention.
Now if you have to support older browsers, then you may want to consider using either the comment or class directives.
My personal preference is to just use the attribute restriction; mainly because people that are new to angular get overwhelmed at first when they see the restrict and it’s variations of the options that can be used.