I have used both ASP and JSP a lot.
I admit that I'm a programmer, not primarily a web designer, but I have to say that although both are fine, I really prefer JSP for sites that require much code (which the original writer's site here may not require).
To me the good thing about JSP is that usually, only one server-side language is required - Java. You use Java both for the bits of code you embed in pages, and for back-end code modules in JavaBeans. (EJBs are an option, but not required except for really major, very high-volume sites, IMHO.)
With ASP, you will be using either JScript or VBScript for the in-page code, then you have to go to something else (such as VC++ or VB) to create COM objects for any serious code modules.
I also just find that Java is more of a "real" programming language than VBScript or JScript, so I find it is more expressive and powerful. That's not to say you can't do everything you need to do in an ASP web site - of course you can.
Another advantage of JSP, of course, is that it isn't tied to Microsoft. :)