I've got both. There's only really a couple differences between them so it's mostly down to preference.
The BK is the more comfortable of the two. The fabric it's made from is softer and more flexible, the HK pack feels a bit more "heavy duty". Not to say that the BK pack is lower quality, they're both excellently made. Just different materials. I've never weighed them but I'd say just from holding them the BK pack feels like it could be half the weight of the HK.
The biggest difference is that the HK packs pod holsters are adjustable so you can set it up for a tighter or looser fit if you want. The HK pack also has far thicker and more substantial Lumbar padding.
That's really all that's between them. Honestly I you won't regret buying either so if you can try both to see which you prefer.