I have the Large Banjo Bros backpack and it is a top-notch product. Great reflective strips.

I have seen the Osprey Radial in the store and I was impressed but I didn't need another backpack at the time.

My daily backpack is a Timbuk2 Swig which I love. I got a custom where I spec'd a huge reflective panel for safer nighttime riding. I think the Swig is discontinued but Timbuk2 has several bicycle backpacks to choose from, most or all customizable.

I love commuting with a backpack, but I am blessed with 3 mile commute and mild weather year round.