Hmmm... no1mad, you bring up a good point that I had not thought much about.
You are right - both the Jannd and Axiom use velcro straps for attachment. The Lone Peak has a buckle which can be cinched down after it has been connected.
I think that the velcro is easier to attach and remove - only because I don't have to fiddle with threading a larger buckle through the type of racks that are on my bikes. (All made by Tubus...) The velcro straps are narrower, thinner, and flexible.
Though I couldn't imagine the velcro loosening up...I would still have to say that the buckles on the Lone Peak are a more secure solution. And in looking back at my pictures - I think that the buckles look better too.
Keep in mind that my Lone Peak is the largest one that they make, the RP-700. If you look at their site:
www.lonepeakpacks.com
It looks like both of the smaller packs, RP-200 and RP-350 use velcro straps like the Jannd. Maybe the folks at Lone Peak have determined that the larger pack will stay more secure over distance with a buckle vs. velcro when expanded and fully loaded.
I used my Lone Peak during PBP last August. It was fully loaded down - and I did not have one issue with it loosening up or needing to be readjusted.
Hope this helps -