Patagonia bags are pretty good, lots of useful pockets on mine. It was too big for me (Critical Mass) and as I had the older model the strap had a sewn in padding, shame it was so long that after adjusting the strap the bag was still hanging behind my ar5e when on the bike. North Face bags are good as well, had the small version and it’s too small, lots of storage and organizer pockets etc but not enough space, had a Large for couple of days and I have to say that medium would be probably perfect. I now have an Osprey Elroy bag and although it’s not a “proper” messenger bag it has all the pockets I need, stabilizer strap, adjustable strap that is wide and a padding pad there as well. What I like as well is the back of the bag is slightly padded and stiffened so the u-lock doesn’t hit my back and if I put some folders inside they won’t be folded and still be nice and straight.
[edit] check Knog bags as well, looked pretty good when I was after one, Wiggle sold out the good looking ones but they are still available in other shops. I remember that Dakine was doing a nice messenger type bag, similar to TNF Base Camp model. TNF has other bags available if You don’t like the shininess of the Base Camp. [edit]