For me a classic is defined more as a car that you grew up seeing and wanted... When I first got into cars the MK2 gti was the one seen on the road so naturally for me that is the classic golf gti.
Was chatting with a mate last week and I was talking about getting a nice example mk2, to which his response was "no way, they are crap, the MK3 is the best". Now bearing in mind that hes a couple of years younger than me its the car that was on his bedroom wall when he was young.
So its probably more down to what appealed to you when you were slightly younger, as opposed to who tells you that something is a 'classic'.