I don't know about 'best', but I certainly can tell you what we've done for our latest project, Voost. https://www.voo.st/
Google App Engine cause we hate doing sysadmin work. Objectify. Cambridge Template Engine with JEXL. RestEasy/HtmlEasy. Jackson. Guice to bind it all together. Front end is heavily CoffeeScript, Handlebars, Jquery, LabJS, customized bootstrap and various other libraries. We've got a credits page full of links to the above projects... https://www.voo.st/about#credits
Overall, I'm pretty happy with this choice. We've had to do some weird and semi-complicated stuff to integrate it all together, but at this point, it works quite well.
Google App Engine cause we hate doing sysadmin work. Objectify. Cambridge Template Engine with JEXL. RestEasy/HtmlEasy. Jackson. Guice to bind it all together. Front end is heavily CoffeeScript, Handlebars, Jquery, LabJS, customized bootstrap and various other libraries. We've got a credits page full of links to the above projects... https://www.voo.st/about#credits
Overall, I'm pretty happy with this choice. We've had to do some weird and semi-complicated stuff to integrate it all together, but at this point, it works quite well.