I am not familiar with that many "big" portlet apps out there that you can look to for an example.
But to answer your original question. Basically there's 3 options worth considering, use liferay mvcportlet / servicebuilder, use spring portlet mvc with or without servicebuilder, jsf with our wihout servicebuilder
Sure there are other frameworks that offer support for portlet development like struts 2, wicket etc but the support isn't that mature and the three options i mentioned seem to be what most people are using
Useing mvc portlet will typically give you the least about of headaches, it's basically the liferay recommended approach to portlet development and it will serve you reasonably well if you are working on mostly simple portlets. But be careful though, their api's are ugly as sin and are not designed with testability in mind. Also be ready to add vast amounts of scriptlets to your jsp's. If you use servicebuilder there are a lot of limitations, like being able to have relationships in your domain model. So your database entities will be dumb data buckets, and in some cases performance will be an issue since you can't easily do joins.
Using spring portlet mvc for porltet development will make you happier as a developer. Because things like dependency injection really allow you to write pretty easy to test code. If the app you are writing is reasonably complex i would go with that unless you're team is already invested in jsf. However prepare to run into all sorts of issues. stupid stuff like jstl el being disabled by default for jsp's and the dreaded classloading related issues. Because liferay uses spring internally these same classes will be both on the portlet classpath and the portal classpath leading to hard to debug problems. Also if you use spring's form taglib your form elements wont have the liferay styles applied to them by default. So if people design a custom theme that changes the look and feel of say all buttons in liferay your portlet wont be affected. You can use spring in conjuction with either servicebuilder or something like jpa 2 / hibernate. Again if your domain is reasonably complex i'd opt to use an orm, unless maybe you really need to take advantage of liferay's cache wich can also be used distributedly
JSF somewhat of a braindead attempt at what wicket does much better. But if your team already is familiar with it his may be your best bet. It can integrate well with spring
