Out of the two your looking at, I think the Osprey looks pretty tidy. The web site was a bit confusing, does it have the AirScape Suspension system?
I've got a Dakine Nomad and a Camelbak Mule. Both 3L bladders. But gear carrying wise, a bit smaller than the two you've listed.
I like the Mule and don't really have any issues with it, but the Dakine is better than the Mule in every possible way. Comfort, design, adjustability, price, bladder design, looks.
Given Dakine doesn't have much of a following in Australia (I got it off ChainreactionCycles) I wasn't expecting it to be as good as the Camelbak. Was quite surprised at the quality of the product and whenever I want gear I always go and check out what Dakine has to offer. Especially if as much thought goes into all their products 
From recent research I've done it'd be tough to go past X's Deuter for carrying a bit of gear (weighty items) on the bike. Seems to have good ergonomics and very good weight distribution in its favour!