I don't think a MK5 is the car to buy as an investment, it's a car you play with for a while and move on, or keep.
@AJP I doubt the MK3 will ever become more valuable, or the MK4 (except the R32). MK5 possibly as it marked VWs return to form. It's a car with one foot in it's history and one foot in modernity, an 'analog' car. The MK7+ is the 'digital age' and a completely different kettle of fish. I don't really look at them as a 'Golf' any more tbh.....just another VAG product off the never ending conveyor belt.
MK3s rot from the inside out with ruthless efficiency, and MK4s were just boring to drive, but nicely made. Agree on the MK1s and 2s. I had them back in the day, but defo will never be going back there