I don't like the whole Animal Crossing game history, because (sorry, but that's my opinion) it's really boring! My Little Cousin and me played it for about 1-2 hours and got bored and we never wanted to play it again...
The first one, for the gamecube, was good, the ds one was ok, but the wii one is the gamecube game put on a wii disk with a bad rolling camera that only works well with the ds.
I've read that there's, as Nerdius said, not much difference between the older versions and AC: City Folk. But I haven't got any earlier versions, so I think I'll buy it anyways...