On the Zenning! blog there's a recent post, the first part of a series, that looks at various web application frameworks both PHP and not (including Ruby on Rails, Prado and Django).
He starts with these frameworks:
He looks at the non-PHP frameworks first to see how difficult they'd be to get into. Despite reservations about the different language structure, he shows favoritism towards Ruby on Rails. He has reviewed the PHP frameworks yet, so it's not a final decision.