So I'm shopping around for a 13" backpack for going back to school in a couple of months. I'm very much into the STM Evolution Small Backpack at the moment as it's got a built in sleeve type thing, water bottle pockets (important) and seems to have general good design happening (padded straps, rain cover, accessory pocket etc... I've read some conflicting reviews on reliability with some people swearing by it, and other people saying the zippers come apart easily etc... I did a bit of searching, but most of the stuff came up for either 15" backpacks and/or messenger style bags. What are people using as their 13" backpacks for school?