In an MVC architecture, servlets are used as controller and JSPs as view.
But both are technically the same. JSP will be translated into servlet, either in compile time (like in JDeveloper) or when accessed for the first time (like in Tomcat).
So the real difference is in the ease of use. I'm pretty sure that you'll have a hard time rendering HTML page using servlet; but opposite to common sense, you'll actually find it pretty easy to code even a fairly complex logic all inside JSP (with the help of some prepared helper class maybe). PHP guys do this all the time. And so they fall into the pitfall of creating spaghetti codes.
So my solution to your problem: if you found it easier to code in JSP and it wouldn't involve too many code, feel free to code in JSP. Otherwise, use servlet.
