I've owned quite a passel of packs. My wife says I'm worse than she is with shoes and purses...

A few years back I scored a Kelty Redwing and became a full on fan-boy of Kelty packs.
The Kelty Redwing is 50 liters which with my warm weather gear I can use it for day hikes on up to 3 days without skimping much on food or gear. For Trips of 2 or more nights I really like my Kelty Coyote, it is about 5,000 cubic inches and unless you have a giant sleeping bag and tent you can load it up with enough gear and food to be on the trail unsupported for at least five days.
The Kelty Redwing is comfortable to me up to ~40 pounds. The Kelty Coyote has been comfortable for five hours + with 50-60 pounds of gear. It will probably do more but I've not had the need to test it beyond that, even with long sections of dry trail between water sources.
Another thing I like about the Kelty packs is the easy access to gear. The new Redwings are a hybrid panel top-loading design that is easy to access gear without having to pull every item out of the pack. The Coyote has center panel access which is also very easy to access gear without unpacking everything.
I find them very comfortable even after having them on for most of the day. Adjustable, multiple sizes available and affordable. The durability has been excellent and the color options Dark Forest and Caper (kind of a Coyote brown) blend nicely with my AO.
I like them well enough to have purchased a Redwing for everyone in my household, a total of five packs. They get regular use, mine is used at least four times a month and this year I'm averaging 7 days / month getting my pack out on the trails. My Kelty packs are near the top of my most used gear.