Lowepro Omni Pro Xtreme 3

Like Goldilocks' porridge, this bag turned out to be the perfect (well almost) one for me after trying many.

What I particularly like is that it can be carried onto an airplane and since it is in a hard case, I don't have to worry about my gear getting banged around in the overhead bin. Even better, if the airport security gives you a hard time, you can send it as checked luggage and because it's a Pelican case you don't have to worry about your equipment getting damaged in that whole process.

If you know you don't need the extra protection you can jettison the Pelican case and carry this around as a shoulder bag. The quick access top flap is a great feature.

Here's what I fit into mine so far with a little bit of room left;

Canon 350D SLR with BG-E3 grip mounted
Canon 70-200 f/4 lens
Canon 10-22 f/3.5 lens
Canon 35mm f/2 lens
Canon 430EX flash
Manfrotto Super Clamp
Manfrotto 3007 Table Top Tripod Kit
Canon EW-83 E Lens Hood
Canon ST-E2 Infrared flash transmitter
Canon battery charger

One downside is that the bag doesn't really come with enough dividers and Lowepro doesn't list them on their web site as an accessory and none of the retailers that I have checked offer them. I am using ones from my Canon backpack in the meantime.

Hard / Soft case design offers versatility and protection
Single storage level makes it easy to see what you have
Lots of storage capacity for a bag this size
Quick access top flap
Decent shoulder strap and carry handle

Not enough internal dividers and hard to get extras

None needed yet