My wife and I traded our 2005 Murano SL AWD for a 2007 AWD SEL+ Ford Edge back in May, and we love our Edge. With just about all the options available, including navigation, the Edge is hard to beat.
We really grew to wonder not IF our Murano was going to "act up"...but WHEN. The biggest problem we had with it was that, over 10 times, it simply refused to go into Park after arriving at our destination. Sometimes my wife would have to sit for 5 minutes or so before it would allow Park to be engaged. That, combined with interior rattles the dealer could never find, convinced us we needed to trade it for a car we could depend on....and I think we have it in our Edge.
For 2008, the Edge with the Sync option would definitely be better than whatever Nissan has in their Muranos. Combine the Sync option with the Navigation in the Edge, and you've got a great system.
And...the Edge is built in Canada....the Murano comes from Japan.