Having posted in the F07 forum, you're likely to get quite a number of responses that are focused on the GT.
Styling wise, you either love it or hate it.
Driving wise, it definitely drives like a large sedan, not an SUV. I'd say that it feels bigger than my E60. I think the xDrive is something you'd have to see for yourself. I ordered mine with xDrive, but that was directly related to a packaging decision made by BMW, rather than a "true need". Stating the obvious, by buying used, you'll have less control over vehicle content, as compared to ordering it to suit your specific needs.
Can't really speak to the ability to tow -- I have an old Expedition for that purpose, so no intention to do so with the F07.
Quite a few people have had less than satisfactory experiences with the earlier F07's, so be selective if you go that route. Also, the hard drive based navigation in the 2010 and newer cars (E60 and F07) is more than a little wacky at times.
Over the last few years, my E60's have not been trouble free:
- '07 525 -- replaced virtually all of the electronics in the console over the first three years
- '10 535 -- replaced Turbo and HPFP at ~ 20k miles; runs OK, but is starting to act like it needs a new hard drive
The 535 wagons have been know to have drainage problems with the sunroof modules, leading to a water-soaked tragedy in the electronics bay, and as many people swear at the N54 engine as swear by it.
So, with all that said, I obviously made the decision to move to the GT. Ultimately that decision was based on "content" or my perception of "value" if you wish. The current GT packs a tremendous amount of technology and comfort at it's price point. Although we've only driven it a few hundred miles, the boss (she who must be made happy) is quite enamored of the GT as a replacement for the E60....
Personally, I'd keep the Touareg for towing duty and explore one of the recent 5-Series (Touring or GT) to use as a daily driver.