Agreed, Nooby, if the OP wants a high-capacity tow vehicle mainly for business use. Amaroks are probably one of the best double-cab pickups; they can tow up to 3500kgs, and carry around a ton in the load bed as well. Later ones are all V6 TDIs with auto gearboxes - perfect for towing with no hassle. They are now heavily cloned with the Ford Ranger; both models share much of the same architecture. These vehicles are huge though, and don't fit in a standard parking bay - beware when popping down the supermarket!
Amaroks may qualify as private cars for business tax purposes, so that could help to sway a buying decision. Touaregs are probably better as everyday/leisure vehicles, but with less carrying ability.
I had a look around an Amarok whilst in a VW Commercial dealer's showroom. Very impressive, but I was shocked to see it had old-fashioned leaf springs on the rear axle! I gather this allows for a heavy loadbed capacity, but still retains a decent ride quality.....apparently.
Having said all the above, I wouldn't be happy to buy a second-hand Touareg that had been regularly used to tow 3.5 tons!