I've owned many different makes of cars and it seems the VW crowd has been the worst IMO. Honda is hit or miss due to the popularity of the cars but it seemed like every VW guys shit didn't stink. Not so much on here but VWVortex was the worst forum i've ever been a part of...
Aside from that I work with a lot of PRicans and from what I can gather from their experiences those guys are cut-throat thieves in the rotary world. No first hand experiences though.
My best is my current Full Size Chevy group. Very helpfull, not biased, just all around good people. I know it's a lot because they are all middle aged "adults" but aren't we middle aged "adults"? Well some of us are...