I've had the Prime Design Ergo rack for a couple years now and still really like it.  It flips down and then drops on both sides (both sides work the same way).

I have one side setup for a 6ft ladder and the other side can take a 10ft or 12ft without any adjustment.  I think I could place an 8ft on the side setup for the 6ft without any adjustments, but don't own a 8ft ladder so haven't tried.