A s4 would be nice if you could afford to do the maintenance. As B said, they're very costly to own/maintain. I have a very young friend that managed to get himself into a s4 by myself by the time he was a junior/senior in high school. He loved the car but eventually sold it off due to the costs of maintaining it. He said it was just too expensive to keep on the road, things broke and were expensive and they broke often.
The quattro system on Audi's is astounding. I love how you can throw 100% of the power to any one wheel on the car, its great. Repair bills and maintenance costs aren't so great.
For the original poster, a lot of cars have been posted that are nice cars but all have their advantages and disadvantages.
RWD sucks in snow.
FWD sucks period, in my mind.
AWD is great, but can be costly if something goes wrong.
If I had $35,000 to spend on a car, I certainly wouldn't buy a car for $25,000 then spend $10,000 on mods. Its just not reliable and you could find yourself with a great giant heap of garbage that won't run. Look at the cash that B dumped into the del sol and how that turned out. This is a tuner site, but $35,000 is no chump change and I wouldn't take my chances risking it on a car that could potentially not work out.
With that said, I also probably would want to buy a brand spanking new car with 5 miles on the car if I were going to spend $35,000. For that kind of money I would want the new car smell, the feel of a new car, the feel of sensitive non-worn pedals, factory sharp steering, a warranty provided by the factory and a whole other host of things rather than buying a car that already had 20,000-30,000 miles of its life used. To me thats just not worth it. Perhaps buying a car that has 10,000 miles on it that was $40,000-$45,000 and getting into a more expensive car that you would usually be able to afford. I definately wouldn't be buying a M5 with 50,000 miles on it for $35,000.
To each its own, there's a lot of choices that could be had for less than $35,000.