I use a National Geographic backpack, medium version for my Tachie and two lenses, 10 holders. Unfortunatly I put the Tachie upstairs in the big open compartment, use a silk pillow case, film holders in a plastic bag in the long lens center area below and lens, air can, loupe and all about the sides. The dark cloth gets shoved in the notebook computer slot from the side. Holds two water bottles, straps for tripod. Does not have a belt to off load the bulk off your shoulders but does a nice job. Mondo pockets and tie points. It gets soggy, in the rain, but keep inside very dry.
I use the Lowepro CompuRover AW backpack. I carry Chamonix 45N-1, five holders and two lenses in the bottom compartment. Filters, dark cloth, other accessories and Domke bag with my Rolleiflex and 35mm RF go to the top. You can also attach a lightweight tripod to the backpack. I favor this setup for the travel.