I use this bag
https://www.manfrotto.us/nbsp-717f75
and love it.
Good Points :
- Holds loads (15" MBP, iPad, chargers and extra lenses)
- Lots of access means it's all easy to get to
- Good padding to keep my kit safe
- Comfortable on the back, even if fully loaded
- Kept my kit dry in all sorts of weather
Bad Points
- Sometimes it's too big when I want to travel light, but then it's not designed to be a 'day bag'
As it can hold it all, sometimes it's heavy. At the moment I just leave the stuff I don't need at home to lighten the load, but I'm thinking of getting a smaller bag for short off trips. Going to check out Kenoh's suggestion (#4 in his list) I think...