Osprey also do fantastic bags
I've got a Farpoint 40 for a travel bag (upto 1 week of travel) -
https://www.wiggle.co.uk/osprey-farpoint-40-rucksack-2
Great bag due to its clamshell design. It full opens like a suitcase but is also a backpack and can be carried sideways too.
Talon 22 for general day use -
https://www.wiggle.co.uk/osprey-talon-22-rucksack-2
I would go for an Osprey talon 33 as a general day bag now actually. Probably big enough to fit in weeks worth of stuff and would go under the seat of a plane based on the new baggage rules for Ryan air and Easyjet