When I was at art school I used a satchel, I still do, because a satchels natural shape is squared so it doesn't crush your books and sketchbooks. It also fit my eee in it just fine.
I also used a builders toolbox, the kind you can get from a DIY store, to keep my art supplies in. It had a convinent handle, various compartments and a little hole for a padlock if I was leaving it somewhere. It was also plastic so if some paint leaked or such it wasn't a problem. Keeping my supplies separate from my actual artwork. I still store a lot of my supplies in it, it's a fabulous contraption.
The main thing is if you have to travel by walking you need a bag that will be comfortable. A satchel can be pretty heavy just on the one shoulder, but I coped with the walk for the convenience of satchel shape XD
I like a toolbox because if at the end of the day I still had wet brushes it didn't matter because the box was plastic and I had none of my art in it, so I wasn't ruining anything by dumping my wet brushes in it. It was a studio in a box.