looking for good tank bag / backpack combo

I'm looking for a tank bag with backpack straps. I see a lot of different ones are available, but I'm worried about how comfortable they are as a backpack. Comfort is a big issue because we often ride out and go hiking for a couple hours. Other features are not as important, but a map pocket would be nice. If anyone has any recommendations I'd like to hear them.
I'm not sure if I want magnetic or strap mount, I've never used either one. Seems like magnetic would be a lot more convenient.

 

This is the one I have and am very happy with. It is very versatile and well made. I think I paid about half of what they are asking for them.

Gears Canada | Sport Star Tank and Tail Bag

:crazy:

 

Rapid Transit Recon 19 Magnetic Tank Bag :: New Enough