Jan Geißler:
Service Builder is completely independent from any WebController framework.
True, but the framework can sometimes interfere w/ the SB portlet.
I tend to create a SB portlet but leave the portlet side alone - just move it to the "hidden" category and otherwise leave the generated view.jsp alone.
Any real portlets will use the service jar and therefore will not "corrupt" the SB portlet's class loader with framework jars.
This separation is not a requirement, you can put them in a single project but take care that everything you pull in and monitor the effects in the class loader.
Which one is better: The one you know better and feel comfortable with. The one which gives you more speed in development. ;)
This is the position that I push most often - use the tools you know. A development project can be a hard time to learn a new framework as you'll always be wondering at each failure whether it is your code or the framework.
Sometimes, however, Liferay MVC can be thrown on you, namely if you have a requirement to use the Configuration panel - this is only supported by Liferay MVC and not by Spring MVC. Spring MVC you can use the general EDIT mode to display settings, but you won't get the expected integration w/ Liferay's Configuration panel.
