What did you decide?
A certain reviewer at AVS and other places, prefers the 790 as of his latest statement, but he's kinda been called out for his recviewing methods. IMO, if you are going to be a reviewer, when it comes to things like AQ and PQ, it needs to be compared to reference, not how sharp or vivid you can make one with the internal image "enhancements". But hey, to each their own.
My opinion on the 790 and 500 is that in the proper modes and with things turned off, for 2D they should be close if not mostly the same. My preference in the Panasonic over the Sony is aesthetics. For what it costs, I dont like the look of the Sony and I hated the menu as well.