I'd vouch for the Kata brand. I've got the R102 backpack, which is currently holding the following for me:
A300 body
Sigma 30mm F1.4
Minolta 50mm F1.7
Sony 18-250mm
Tamron 10-24mm
Tamron 200-500mm big zoom
Sony HVLF42 flash
bulb blower
sensor brush
5 filters
wired remote shutter release
large microfiber towel
battery charger, video cables, USB cables
Sony T100 ultra-compact plus charger and wires
Here's a pic with almost all the above, except the Tamron 10-24mm which hadn't arrived yet...but you can see I've got a space for it:
Not quite as much as you, but the body plus 5 lenses and a flash is no problem, and there's still enough room for accessories. The cavity for the camera body is plenty deep - enough so that you can hold a full frame body with vertical grip and big zoom mounted on-body (I got the bag because I needed one that could handle my A300 with the Tamron 200-500 mounted...this was one of the very very few!). Note that the 200-500 is off to the side in the shot above - when I mount it on camera, I place the 18-250mm in the side space, then move that divider from the center to the side, with the 10-24 moving above the 18-250. Then, the 200-500 can sit mounted on body in the entire center section. The lid holds the wires, filters, and chargers in side zippered pockets. And the space between the camera body and the lid is around 5 inches...meaning a vertical grip or tall full frame body would fit no problem.
Also notice in the top right corner of the bag is the rain cover in its bag...this can be stored elsewhere in the lid, or strapped to the outside of the bag, opening up additional room for another smaller lens there. I didn't need the space (yet) so for now the raincover resides there unless I need it.
Perks to the bag include the armored exterior (these guys build military spec packs, bullet proof vests, and professional war-zone photojournalist stuff), the rain cover, the quick access door within a door (you can open a smaller inner flap to remove just the camera body and mounted lens, without dumping the rest of the bag's contents on the ground...the main lid can remain securely closed), the ability to change the interior dividers as you need, and purchase more divider material to cut and design as many chambers as you need, the Yelloop interior material which is very soft and vibrant yellow color to make equipment easy to see and distinguish, the very comfortable and wide straps with excellent pack balance designed for long hauling a lot of weight for long distances (there's that military expertise again!), excellent and hardy strap and support systems for plenty of accessories such as tripod holders, waist packs, water bottles, front packs, and camera strap loop mounts on the front of the shoulder straps to take the camera weight off your neck when its outside the bag.
Obviously, check their line to see if the next bag size up or down would be better for you - the only question I would have is whether there'd be room for 2 bodies, flash, and more than 3-4 lenses. I think it would fit - but you'd probably need to buy more dividers to make extra chambers.