I've had #1 (Maier) and current have #2 (Machine Art). I really like the Mud Sling as I think it fits better and has cleaner look IMO. I also had a Wunderlich model on my 2008 GSA that stunk - poor fit, required adding foam tape to the frame, and let too much water through over the top.

2013 R1200GSA 90th
2005 R1200RT
1996 R850R