Halloween Horror Nights vs Fright Fest vs Scary Farm?

It's that spooky time of year again! Anyone here have thoughts about the big scary amusement park events in the area?

Universal Studios Halloween Horror Nights vs
Six Flags Fright Fest vs
Knotts Scary Farm

For people who enjoy these scary, fun events, which do you prefer most? Are there other Halloween events in Los Angeles you prefer more (Los Angeles Haunted Hay Ride or Queen Mary's Dark Harbour, for example)?