what cities do you consider well designed and why?

Montreal is nice. Most people, even as far out as Outremont, have a grocery store within walking distance. Metro map could be improved but is decent for the core. Transit runs decently during peak times. Main issue is lack of bike lanes, but there's always a shortage of bixis so apparently people do cycle. Easy access to parks, I've got two within walking distance. Unfortunately the metro does stop at around 1a, so going on a downtown bar until closing means you're taking a night bus back.

I agree. Montreal is better than Vancouver. They have a really good mix of height limited multi family zoning and commercial streets.

Tokyo does well. Ubiquitous public transit does wonders. Singapore is supposed to be pretty good as well, but I’ve never left Changi to tell.

There aren't any, really; because we didn't spend the 20th Century thinking of alternatives to commuting via personal automobile from bedrooms to offices.

A true well designed city have not been tried yet.

Do you actually design a city, waterfall style? Wouldn't you just end up with Canberra, the most boring city ever, or Disney World?

Yes, just like with communism, to which I alluded in my comment, with urban design we also have a problem of figuring out what people want, where, and how much of it. The “urban design” people often have the similar mindset to communist planners, who knew better what people should want than the people themselves.