If you want to find one group who completely and decisively hates Bloomberg though, just talk to cab drivers. The things that he did regarding new medallions and all of the bullshit with the TLC the last 8 years have made most old-timers quit. The mere mention of the guy's name will bring out some pretty big curse words.
The funny thing is though, most of the crime in the city peaked during the Koch era. He started some of the things that Giuliani and Bloomberg later got credit for. Dinkins gets saddled with a lot of the worst memories of it mostly because of how ineffective he was as Mayor.
Koch did some right dickish things to outerborough New Yorkers though. The closing of bike/pedestrian traffic on the Queensboro Bridge will always stick out in my memory. Caused a 3000+ bike protest down Park Avenue... and a couple years ago they named the fucking bridge after him. >_<