The Harbin subway system -- which has been in the process of being built, with no viable progress, for almost ten years.  The opening date for the No. 1 line has been pushed back for almost that amount of time and construction is supposedly underway.

My city has no subway

GZ subway is quite nice. Sometimes way too crowded, but that is nearly unavoidable at times in a city of 14mil.

I was surprised to read on a Harbin website that the Harbin metro will actually open early in the New Year and that they have been doing trial runs on Line No. 1.

Shanghai, Line 6. short - 4 wagons only, and 25.398 people each station for every 6-12 minutes interval

When I was in China...Beijing Subway Line 1... oye vey. We called it the Migrant line. Spitting, yelling, fighting and the Stench... dear GOD the stench. 

Best in Beijing is line ten! 

then there's line 13, or as my friend called it, "The garlic line" cause that's what it smelled like for some reason. 

Shanghai,Line 2

it is too cold in summer.Caught a cold.

askyoung, line 2 is fine.  Line 1 and 3 are the worst.  They both go to the train stations so they're full of dirty poor country folk (down vote that all you want but its true) and so the subways already look old and dirty.  Plus you can never get on because they're full of people's luggage as they come and go from the train stations.  I think line 3 is slightly worse than line 1.

Line 1 or Line 10 always crowded, Line 1 is old, Line 10 is nice but way too crowded....

My current city has no subway.  In Beijing agree with line 1 and 10 also had to take the Batong line in morning and had to wait for 3 trains to go by as people faces squashed against the windows.  GZ was crazy people just piling on to the subway and they have no concept of a full train.  Hong Kong was the most pleasant, where people super polite and know when a train is full- though did see a guy dashing for the train and getting half his body inside and half outside that made me laugh.