I don't really recommend going backwards in the series, to be honest. While some good things did get lost between games, NL is much, much better than the older games. I haven't touched an older AC game since I got it. Plus, there's no more wi-fi for Wild World and City Folk. If you're going to pick up any older AC game, I'd recommend the first one.
I think AC works best as a handheld game as well. I honestly don't know if I'd buy a Wii U AC for that reason alone.