However, I don't tend to agree with everything on the site, so here we go!
Overall purpose: Travel as light as you can, but still be able to have "everything" with you.
Personally I set a maximum weight of 10 kg.
The bag is the most important thing when travelling. I visited several shops and finally found the bag.
1. Top quality and good design. It should not break after the first couple of trips, nor the next 5 years.
2. Light weight, max 2 kg
3. Non-wheeled. I absolute hate wheeled luggage. You get more room and frankly, who can't carry 10 kg?
4. At least 2 main compartments.
5. Separate room for laptop.
6. Side pockets.
Unlimited. Yes, unlimited as long as the above criteria was met. It will be a bag I will have as my friend for many years to come.
..And the winner is...
Price in UK: £395, US: $395
Rather expensive, so I went on Ebay and found the bag to $220. With shipping and custom duty in the UK, the final price ended at £220.
It has the max dimensions for carry-on luggage and weighs 1.9 kg.
Details (from Tumi website)