I have a couple of SWISS backpacks that I like. Great bags, good size, and durable.
I am a bit disappointed in color choices (many brands). For cyclists, and even pedestrians, bright colors are important. Yet, so many brands like black and dull colors.
The most common pack that I take is an old Camelback Mule. I think the bladder went bad a while ago and I haven't replaced it (it makes a nice pocket for papers & etc).
Mine is similar to this one. Unfortunately discontinued, and now getting well worn.
The size is small, but great for my needs. I like the two open top external pockets/compartments. And, I often have had way more stuffed into the pack than it was originally designed for.
I'd probably move the tiedowns around a bit. I never use the belt as a belt, but use the straps periodically, so better positioning for the two long straps would be good.