No direct experience whatsoever, but both Granite Gear and ULA have legions of enthusiastic fans. Methinks that when you've narrowed your choices to the final two or so -- it may be well worth it to buy them both -- to better try them out with your own gear. It's the best and sometimes the only way to know for sure how well they carry and how easily they pack. Return postage is pretty minimal -- esp. when compared to your investment and the importance of fit/comfort.

For me, if GG carries significantly better, then I would go for it. But if both are comparable in the comfort department, then I would go for the ULA -- for weight saving and ease of use. For one thing, I very much dislike backpacks with floating tops and myriad of straps. Secondly, I also dislike packs with a design that makes it exceedingly difficult if not impossible to pull out / put back a water bottle without having to take off the entire pack. Not a problem if you always use an internal bladder, but bad, bad side pocket/strapping design for bottle users.