Very nice review. I love the Avernum series. Trying to decide if I want to try Avadon or Geneforge.
If you can stomach the old Geneforge graphics, you might want to go with that. You seem to like open worlds, and Geneforge is one huge island you can explore as you like (The map works a lot like Baldur's Gate 1). I might start with Geneforge 2, though, as the first two Geneforges suffer from being very similar, and 2 in my opinion is a little bit more polished and balanced. I say Geneforge is my favourite Spiderweb game, but that's because I played it first. Had I played part 2 first, I'd probably have considered it the better part.