I was fined thirty quid the other week for driving down a bus lane in Reading that I felt I was forced into by the bizarre one way system so yeah, I'd say there.
Ouch, yeah Reading is a bit crap and has quite a confusing (and large) one way system. I used to go to a scuba diving club in Preston Park on a Thursday night and always got confused trying to leave the city.
Going to vote Helsinki as there are lots of roads that share use with trams. There are times when the trams have priority and times when cars do and it isn't always obvious what's going on. Had one scary moment driving head on towards a (stationary) tram before turning off - won't forget that in a hurry. Pretty sure it was correct but still very scary.
Then it has to be London. I work there though so I'm used to it. Wouldn't want to be a tourist trying to read signs to navigate the south circular!
Tampa's very confusing. There's a bit that reminded me of spaghetti junction with loads of flyovers. Gross.
Cities I've driven in that are all fine: New York, Tokyo, Phuket, Houston, Paris (busy but not the worst), Rome, Brussels (hate the bloody ringroad though), Stockholm, Hamburg, Amsterdam, Copenhagen, Saltzburg...probably lots more.