Right...........................................
Going to sound like a boff now but I only know the following because I've spent my life surrounded by professional climbers and my Dad, who is an outdoor equipment expert from his :cough: youthful climbing days and his rucksack obsession- i kid you not!
Arcteryx are probably the best on the market. Snappy design, lightweight and new materials and fully waterproof. The zips are seamless to keep water out. They have designs in all shapes and sizes. I wear their jackets to football as they are unique (got to look good on the terraces), and designed in such a way, light material, waterproof etc.... BUT..........they are mega expensive in everything they make. For rucksacks and jackets you are looking at £200-500 if not more.......
North Face, are similar to Arteryx, same in design and material, have reasonable to mega expensive prices. All my holiday travel bags are made by North Face, as they use a rubber material which makes them quite unique and people always ask where I got them.
Because of my Dad, I'm a total snob when it comes to travelling with good bags. I'm not talking Burberry, Louis Vuitton shit either
Karrimor is next down the ladder- not as expensive or snappy, but you will get something that meets your requirements for a very, very decent price, and waterproof, but the materials and design will not be so cutting edge.
Gregory, is an "antique" make which again has many years of proven history. Again, not so cutting edge but you'll get a good price and it will function in all the ways you require.
My advice is, go in an outdoor shop, have alook at some rucksacks and make a note of the LITRE size you are looking for. Go on EBAY, you will find ALL of the above rucksacks on there for prices between £5 upwards and all that meet your requirements. My Dad has parcels flown in on a weekly basis that contain all kinds of rucksacks etc... that he's managed to buy for cheap and add to his ever growing collection! All good makes, quality and names!