Horses for courses, really. The only thing I would add, considering that this issue has been flogged to death elsewhere, and ignoring such mundane issues as your price sensitivity, is that if you are a tourer (as in GT mode which means a really long-legged, economical, high-speed 4-door touring car with acceptable ride and tonnes of room), get a 6. If you have family, get a 6. If you are in WA, the chopped-up country roads here indicate that a 6 might be better due to its longer wheel base and improved ride quality. If you drive dirt roads, ditto, as the AWD 6 is great on dirt and the longer WB improves longitudinal stability.
If you are a short distance, single or no family point-and-squirt driver and spend more time in urban environments, you might consider the 3. That said, I spend a fair amount of time in the city and still have a 6. If you are urban in the major cities, many of the roads are better than here in WA and you may better be able to live with the slightly choppier ride of the 3, a result of its shorter wheelbase. Plenty of people do, obviously.
Having said all that, there are many who find exceptions to all of the above, and I would find it hard to refute them.
My only annoying rattle was traced to the drivers seat mount bolt. Tightened and never had it again.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18