here's my opinion...
when i started photography, my first bag was a crumpler. it was trendy, solidly built, loud and no regrets. then my equipment list started to expand and eventually, the bag became smaller...(hahaha) tried squeezing lots of things and it was heavy as hell. no choice but to buy a bigger bag so i tried a lowepro, its the reporter 650AW (biggest). it was the best sling bag ever...can carry all the stuffs including a laptop and very well padded for protection. it can also be quite versatile too. used it as a utility bag for all kind of activities. cost half of the biggest crumpler and never disappoint me till this day. the black is a bit boring but it can never goes wrong in any occassion.
have 4 to 5 lowepros since and realised something...its not about the bag, the equipment or the camera...its the photos! really no point carry the most trendy. loud and expensive gear if the photos you take is consistently mediocre and not improving. rather spend the money on more photo books to hone the skill. own a few pretty decent L-lenses but nowadays only carry the body and 1 wide angle...this setup covers almost everything and great distances too( too much equipment its like full battle order in my army days...shack)
oops..too long winded here...hope my experience is of good use....cheers