Another vote for the 1.9 TDi PD130 here
I have a 53 plate 1.9 TDi PD130 Quattro Sport saloon that I've owned for 3 years. Its the best car I've ever owned to be honest and I've no idea what to go for next lol.
The engine isn't the smoothest or the quietest (my missus' 2007 2.0 TDi Cabriolet is smoother and quieter) but I love its punchy power delivery and how easily it revs. The PD units have a nice wide power band IMO compared to some modern diesels and its a very driveable car.
The Quattro drive train is epic in the snow and inspires confidence even if the Sport suspension does roll a bit in the corners. If you get too lairy then the back end steps out which is also good fun.
Mine has the cloth interior which has worn well even though the seats do mark quite easily. They are pretty confortable though and both the driver and passenger seats have an electric adjustable lumbar support. I'm 6ft 4ins tall and there's plenty of room for me.
Mine has 127,000 miles on the clock and I service it myself every 9-12 months. I can't fault how its run for me. It drives like its got 40,000 miles under its wheels and the mechanicals feel bombproof.
With a mixture of town and b-road driving I generally get between 37-41mpg which I think is pretty good for the performance of the car. I'm definitely considering a remap though as I've heard many good things about them. Many people do tweaked remaps which alter the power delivery so that the engine doesn't dump too much torque low down which hammers the clutch.
I've heard from reliable sources that the engine puts out more than the quoted 128bhp & 229lb/ft from the factory. The quoted 0-60 time of 10.1 seconds is also a conservative estimate. Its a quicker car than you might think.
The Quattro drivetrain seems to be kind to tyres too with even wear on the fronts and very little on the rears with a properly set up car. I've had over 20,000 miles out of a set of fronts before which was great after being used to a Seat Leon Cupra R 225 that ate rubber for fun.
As is always the case with PD engines, just make sure that the car has been serviced regularly (ideally every 12 months minimum) and that they have used proper PD oil when doing so. Many PD engines have been ruined by people using the wrong oil that can generally destroy the cams at higher mileages. The PD150 engine found in the Golf, Bora and Leon really suffers with this.
I'd also recommend getting the EGR valve and Intake Manifold properly cleaned and then the EGR blanked off. Higher mileage cars generally get very sooted up and eventually this kills the turbo, which can be expensive to get properly reconditioned. Get yours cleaned out fully and then blank off the EGR to stop the soot building back up. Costs peanuts and could save you a fortune.
The steering wheels usually wear smooth and the buttons on the aircon unit tend to rub off with time but there are kits on ebay where you can stick new covers on them to tidy it all up.
Look out for the water in the footwell too. This is caused by drainholes under the battery and brake servo getting clogged up so that water running off the windscreen builds up under the bonnet. A simple fix can also save lots of pennies.
All in all superb cars that are well worth the money. They have class and quality in abundance and still look the part too.
The end of line S-Line models are particularly nice too. They only came in 1.8T 190 spec and usually have full leather too. The 18in S-Line alloys particularly suit the car and with the OE mudflaps it looks great. My favourite colour is the Akoya Silver in this spec, though scarlet red looks awesome too.
The 1.8T engine is prone to coil pack failures and if my Seat Leon was anything to go by the electronic boost valves can play up at higher mileages. Its also not the smoothest engine and can sound quite thrashy at higher revs and motorway speeds. It is very tuneable though which is nice.
I struggled to get anywhere near the 32mpg average the factory claimed with this engine. Even with driving like an old dear I rarely got more than 28mpg and so I imagine with a heavier Quattro drivetrain I would expect economy to suffer further. Also road tax isn't cheap due to the high emissions.
All in all, I don't think you can go too far wrong with a B6 providing you do your homework. This forum is an excellent place to be with loads of very helpful people.
Good luck!
J