My wife and I have a few... She uses an MEC bag and like others here just loves it. She has two sizes and even used one as a purse for years. Light, strong and compact. Recommended.
I have a Crumpler (for my DSLR and stuff) which is nice but I am finding is too bulky - I want to go even smaller. It is light for a camera bag though. Plus it likes to pool a bit of water on the sides when it rains. Crumpler makes some really nice non-camera bags - I would suggest looking them over.
I also have a Timbuk2 while it doesn't have a zipper is very pickpocket safe. Not only are there two clips but a boat load of Velcro that is loud enough to wake anyone - excellent bag and it does have a top handle. The Timbuk2 actually became my standard work bag now and while it only has 2 return flights on it, I love it. Fully water resistant too. The version I have includes a padded laptop compartment which would make it, in my opinion, far too heavy for pack-light travel in Europe.
Plus I have an Eagle Creek which is almost the best of both worlds - strong, lockable zippers and it has worn very well. This was my main workbag for almost 8 years and probably went on over 100 flights. Eagle Creek makes really good products and if you can find one in the size you want you shouldn't hesitate. Just watch the design of the zippers on the top for water resistance. Mine leaked in the rain just slightly.
Pete