In reply to Inspironator: All will be good, there are others out there too
Lowe Alpine, Montane, Macpac, Crux, Gregory, Grivel, Mountain hardwear
you're choosing quite a big size is that whats recommended? manufacturers sizes vary too, rucsacs are not like beer or fuel and not under weights and measures rules
best advice is go to shop, try on with weight in (best method is to take the stuff you are carrying and pack it, then its real weight, not fake sand bags etc. plus you know it fits)
HTH