In my limited experience, DFW, ATL, DEN and STL all have been very nice and accommodating. I live in DFW, so I know the tricks and when not to ask for something, so maybe that helps.
AUS class Charlie is a mess. It needs to be a Bravo with the traffic they have there. San Antonio Charlie are as nice as can be. They vectored me into land there a couple of weeks ago to get me in before a thunder boomer was going to hit. Just don't try to taxi out of there during their morning push....found that out the hard way one day after clearing customs there in 100 degree heat and waiting for 30 minutes for my clearance.
Chicago can be a bit nasty, but not nearly as nasty as Madison approach during OSH. Those guys are the worst I've ever encountered. Milwaukee were as nice as pie and after they handed me off to Madison, the guy cancelled my FF and yelled at me to get off his frequency. Chicago did yell at me to hold my altitude on the lake front at 2,000 when I was getting bumped around by thermals and jet wash.
Nicest controllers I've ever dealt with were at Moline, worst, easily Madison. Some of the Class D's around here have a few jerks, but that's life I guess.