RJasonKlein's post sums it up fairly well IMO.
Our RCE Yellows change the ride quality...in some ways it's slightly better, in some ways slightly worse. Some might call it an improvement. BUT if your main goal is to improve ride quality, I'm not sure they're the best choice if you're limiting yourself to 1 modification.
Also, I would check your local forum to see if anyone is willing to give you a ride on RCE Yellows or any other option you're interested in. Keep in mind the OEM shocks have changed slightly over the years and different tires can make a big difference.
I would choose the Bilstein B6 over the Konis if the goal is to improve ride quality. So my vote is option C, none of the above.
EDIT: or find a deal on some sachs/sacks!
- Andrew