I'm leaning more and more to ultra light. I'm obviously not there but I only plan on my outfit weight shrinking so I don't want to go any bigger. I recently did 30 miles in 3 days with a 2650 kelty redwing loaded with just over 35lbs. I've cut that packs weight down to 25 ish with food and water. I don't plan on carrying over 30 lbs ever again!
I'd like to add that if your going to go for that kind of weight. You should consider a pack one size up. In all the reviews of Gregory packs I've read. The Z65 is pushing it with over 35lb-40lb loads.
I was also looking for a lighter pack than my former military issue ACU Rucksack. The Gregory Z65 comes in at 5lbs. That's half the weight. So for me they were very light weight. Not ultralight. But lightweight.
Since there have already been some great recommendations here, all I have to say is that there's really no wrong choice of Gregory pack! Make sure it's the correct size, but other than that, if it's a Greg, it's an outstanding pack!