RouteLink takes the name of a route, so if your route names are reliable and fairly unique then this will be the same even if the action name to be used changes. ActionLink links to a specific action of a specific controller instead. I use both in my views, depending on what kind of link I'm after!
Html.ActionLink() makes it easy to generate ActionLinks fast, and will give you basic control over what is rendered. If you don't have too many routes, or don't need to give too much or too specific information, this will do the work just fine.