In reply to blyth001:
Depends on what you want to use it for. I bought a 85 l Fjällräven Kajka pack for extended trekking trips in polar regions. The rucksack is also available as 75l and 100l versions. The carrying system is the best I have ever used, especially the hip belt is great in transferring heavy loads to the hips. But of course it is not ideal for technical climbing.
CB