Bigger or more features does not really mean better. The best thing to do is apply some of the practical experience that you should have picked up in the army or otherwise for anyone else. What you should be looking for is something comfortable and durable that will do the job without cpmplications.
Until recently I have been using a 45 litre
One Planet Mad dog day pack for 2-3 day walks. The point is that this pack might not have the best harness, but I can pack light to move fast and there is nothing complicated or fancy that will break. On weekdays it makes a good daypack.
On the other hand I just purchased a much larger pack, a
One Planet Strezlecki (85 litre), which is a lot bigger but necessary for extended trips. Although this pack has a superior harness system you will also find that One Planet use the exact same harness on a number of the better priced packs. While these generally use a less water proof and abrasion resistant fabric, they are often lighter and if you are sensible you will place anything that needs to be dry in a wet bag. The fabric on my small One Planet pack has held up fairly well to punishment. The on thing I will add is that I previously enjoyed using an older double compartment
Berghaus pack. However, I have found that the lower compartment zip on the Strezlecki can be awkward to close. Regardless - when properly adjusted – the harness on the Strezlecki sits well and is comfortable.
Wilderness Equipment (Sea to Summit, http://www.seatosummit.com.au/) is one brand of well made quality packs that have not seemed to receive much of a mention on the forums. I have a Wild Child kid carrier and find the harness very comfortable. Like One Planet, Wilderness Equipment uses the same harness over a range of packs. In particular, a model called the
Breakout is a very rugged, very well priced and good all round sized single compartment pack
. While it has not got all the bells and whistles it can still be guaranteed to do the job. Even though Wilderness Equipment have avoided the use of zips on the Breakout, as stated these can often be awkward and in the worse case scenario – especially on inferior made packs - can break. I would hate to have to open a caught zip in near or below zero temperatures.
As far as the
Macpac are concerned, they are another quality pack but to be honest I find that the harnesses are a bit outdated and they are relatively overpriced
.
In summary, have a good think about how long you your average walk will be and stick to a simple but quality design. A good alround pack is about 60 litres, which is too big for day trips, and borderline big enough for extended walks. Of course the best thing you could do is get the sales assistants to load the packs up and see what feels best for you.