Vaadin is a great framework for building business apps. But it has little support for eye candy, if you need that. Using all java and a swing-like foundation, you can build a responsive ajaxy portlet app. Cons are the eye candy, double theme maintenance, largish server side footprint per user, and lack of a lot of experience in the states, but pros are the ease of portlet creation, built-in ajax support for highly responsive apps.
Spring mvc and liferay mvc have the same similar pros/cons. You'll be coding in JSP, and (depending upon tag libs you use) may have to do your own ajax stuff (if you use AUI/Liferay MVC, you can get some ajaxy support). Usually very light server side footprint so it scales well (in fact it's the best option if you have to scale to hundreds of thousands or millions of users).
Choice depends upon your teams experience and the requirements for what you're going to build.
