Not to be snide, but if it's worth your time to consider a framework choice, then it's also worth your time to stand up some spikes against you most important couple of high level user stories. Both Struts2 and Spring MVC 3 have very easily set up demo enviroments, i.e. you can get a maven archetype running out of your IDE in less than 5 minutes.
I've been involved in panel discussions about which framework is better, and I truly believe that no amount of discussion is worth the time. You're much better served by playing with the frameworks in the context of your use cases.
