I'm using a Revelate Vischacha. I'm not sure how widely available they are in the rest of the world though. Lots of companies have copied it. I was interested in the Ortlieb copy for a while. The secret to the Revelate is thei nterior strap. I still think it could be a little easier to use, but I try to keep things organized by bags and put the stuff that I'm less likely to use further into the bag.
I would say the main annoyance I have with it is the spot tracker bag doesn't always face the sky if the bag isn't pretty full.