Which laptop backpacks are best for travel and work?

I'm a computer technician and I travel a lot for work because most of the work entails onsite repairs or system updates. And so I'm trying to find a laptop bag best suited for work and travel. I'm not sure about the budget though. I've browsed online on Alibaba.com and Amazon trying to find the right one. I think that the best quality laptop bag shouldn't just be a bag but also a tool that plays a part in my work productivity. Of course everyone has their own unique style. But there are those common features that I look for in a laptop backpack such as capacity, security, style organization, durability and weather proofing. The best brands, by the way I've come across quite a number online, design backpacks considering these features and some have add-ons such as USB charging ports for on the go power. I also think that a good work backpack should essentially keep you organized but should also be ideal for travel. So with all these in mind are there any recommendations for backpacks or perhaps stores?